diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 2f33708d..527a868d 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -8,6 +8,7 @@ Amit Jimiwal <amitjimiwal45@gmail.com>
 Athan Reines <kgryte@gmail.com>
 Brendan Graetz <bguiz@users.noreply.github.com>
 Bruno Fenzl <brunofenzl@gmail.com>
+Chinmay J <86140365+JawHawk@users.noreply.github.com>
 Christopher Dambamuromo <chridam@gmail.com>
 Dan Rose <danoftheroses@gmail.com>
 Daniel Killenberger <daniel.killenberger@gmail.com>
@@ -36,6 +37,7 @@ Ognjen Jevremović <ognjenjevremovic@users.noreply.github.com>
 Philipp Burckhardt <pburckhardt@outlook.com>
 Prajwal Kulkarni <prajwalkulkarni76@gmail.com>
 Pranav Goswami <goswami.4@iitj.ac.in>
+Praneki <97080887+PraneGIT@users.noreply.github.com>
 Pratik <97464067+Pratik772846@users.noreply.github.com>
 Ricky Reusser <rsreusser@gmail.com>
 Robert Gislason <gztown2216@yahoo.com>
@@ -44,6 +46,7 @@ Rutam <138517416+performant23@users.noreply.github.com>
 Ryan Seal <splrk@users.noreply.github.com>
 Seyyed Parsa Neshaei <spneshaei@users.noreply.github.com>
 Shraddheya Shendre <shendreshraddheya@gmail.com>
+Shubham <shubh622005@gmail.com>
 Spandan Barve <114365550+marsian83@users.noreply.github.com>
 Stephannie Jiménez Gacha <steff456@hotmail.com>
 Yernar Yergaziyev <yernar.yergaziyev@erg.kz>
diff --git a/is-well-formed-string/README.md b/is-well-formed-string/README.md
new file mode 100644
index 00000000..b667b2a9
--- /dev/null
+++ b/is-well-formed-string/README.md
@@ -0,0 +1,151 @@
+<!--
+
+@license Apache-2.0
+
+Copyright (c) 2024 The Stdlib Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+-->
+
+# isWellFormedString
+
+> Test if a string is well-formed.
+
+<section class="usage">
+
+## Usage
+
+```javascript
+var isWellFormedString = require( '@stdlib/assert/is-well-formed-string' );
+```
+
+#### isWellFormedString( str )
+
+Tests if a `string` is well-formed.
+
+<!-- eslint-disable no-new-wrappers -->
+
+```javascript
+var bool = isWellFormedString( '' );
+// returns true
+
+bool = isWellFormedString( new String( '' ) );
+// returns true
+
+bool = isWellFormedString( '\uDBFF' );
+// returns false
+
+bool = isWellFormedString( '\uDBFFFF\uDBFF' );
+// returns false
+
+bool = isWellFormedString( [] );
+// returns false
+
+bool = isWellFormedString( '-5' );
+// returns true
+
+bool = isWellFormedString( null );
+// returns false
+```
+
+#### isWellFormedString.isPrimitive( str )
+
+Tests if a `string` is a well-formed `string` primitive.
+
+<!-- eslint-disable no-new-wrappers -->
+
+```javascript
+var bool = isWellFormedString.isPrimitive( '' );
+// returns true
+
+bool = isWellFormedString.isPrimitive( new String( '' ) );
+// returns false
+```
+
+#### isWellFormedString.isObject( str )
+
+Tests if a `string` is a well-formed `String` object.
+
+<!-- eslint-disable no-new-wrappers -->
+
+```javascript
+var bool = isWellFormedString.isObject( '' );
+// returns false
+
+bool = isWellFormedString.isObject( new String( '' ) );
+// returns true
+```
+
+</section>
+
+<!-- /.usage -->
+
+<section class="examples">
+
+## Examples
+
+<!-- eslint-disable no-new-wrappers -->
+
+<!-- eslint no-undef: "error" -->
+
+```javascript
+var isWellFormedString = require( '@stdlib/assert/is-well-formed-string' );
+
+var bool = isWellFormedString( '' );
+// returns true
+
+bool = isWellFormedString( new String( '' ) );
+// returns true
+
+bool = isWellFormedString( '\uDBFF' );
+// returns false
+
+bool = isWellFormedString( '\uDBFF\uDBFF' );
+// returns false
+
+bool = isWellFormedString( [] );
+// returns false
+
+bool = isWellFormedString( '-5' );
+// returns true
+
+bool = isWellFormedString( null );
+// returns false
+```
+
+</section>
+
+<!-- /.examples -->
+
+<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
+
+<section class="related">
+
+
+</section>
+
+<!-- /.related -->
+
+<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="links">
+
+<!-- <related-links> -->
+
+
+<!-- </related-links> -->
+
+</section>
+
+<!-- /.links -->
diff --git a/is-well-formed-string/benchmark/benchmark.js b/is-well-formed-string/benchmark/benchmark.js
new file mode 100644
index 00000000..e57bd36c
--- /dev/null
+++ b/is-well-formed-string/benchmark/benchmark.js
@@ -0,0 +1,220 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+/* eslint-disable no-new-wrappers, no-undefined, no-empty-function */
+
+'use strict';
+
+// MODULES //
+
+var bench = require( '@stdlib/bench' );
+var isBoolean = require( './../../is-boolean' ).isPrimitive;
+var pkg = require( './../package.json' ).name;
+var isWellFormedString = require( './../lib' );
+
+
+// MAIN //
+
+bench( pkg+'::primitives', function benchmark( b ) {
+	var strs;
+	var bool;
+	var i;
+
+	strs = [
+		'',
+		'\uDBFF',
+		'Hello World',
+		'3.14',
+		'\uDBFF\uDBFF',
+		-4.0,
+		NaN,
+		true,
+		false,
+		null,
+		undefined
+	];
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		bool = isWellFormedString( strs[ i % strs.length ] );
+		if ( typeof bool !== 'boolean' ) {
+			b.fail( 'should return a boolean' );
+		}
+	}
+	b.toc();
+	if ( !isBoolean( bool ) ) {
+		b.fail( 'should return a boolean' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+'::objects', function benchmark( b ) {
+	var strs;
+	var bool;
+	var i;
+
+	strs = [
+		[],
+		{},
+		function noop() {},
+		new String( '' ),
+		new String( '\uDBFF' ),
+		new String( '\uDBFFFF\uDBFF' )
+	];
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		bool = isWellFormedString( strs[ i % strs.length ] );
+		if ( typeof bool !== 'boolean' ) {
+			b.fail( 'should return a boolean' );
+		}
+	}
+	b.toc();
+	if ( !isBoolean( bool ) ) {
+		b.fail( 'should return a boolean' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+'::primitives:isPrimitive', function benchmark( b ) {
+	var strs;
+	var bool;
+	var i;
+
+	strs = [
+		'',
+		'\uDBFF',
+		'Hello World',
+		'3.14',
+		'\uDBFF\uDBFF',
+		-4.0,
+		NaN,
+		true,
+		false,
+		null,
+		undefined
+	];
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		bool = isWellFormedString.isPrimitive( strs[ i % strs.length ] );
+		if ( typeof bool !== 'boolean' ) {
+			b.fail( 'should return a boolean' );
+		}
+	}
+	b.toc();
+	if ( !isBoolean( bool ) ) {
+		b.fail( 'should return a boolean' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+'::objects:isPrimitive', function benchmark( b ) {
+	var strs;
+	var bool;
+	var i;
+
+	strs = [
+		[],
+		{},
+		function noop() {},
+		new String( '' ),
+		new String( '\uDBFF' ),
+		new String( '\uDBFFFF\uDBFF' )
+	];
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		bool = isWellFormedString.isPrimitive( strs[ i % strs.length ] );
+		if ( typeof bool !== 'boolean' ) {
+			b.fail( 'should return a boolean' );
+		}
+	}
+	b.toc();
+	if ( !isBoolean( bool ) ) {
+		b.fail( 'should return a boolean' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+'::primitives:isObject', function benchmark( b ) {
+	var strs;
+	var bool;
+	var i;
+
+	strs = [
+		'',
+		'\uDBFF',
+		'Hello World',
+		'3.14',
+		'\uDBFF\uDBFF',
+		-4.0,
+		NaN,
+		true,
+		false,
+		null,
+		undefined
+	];
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		bool = isWellFormedString.isObject( strs[ i % strs.length ] );
+		if ( typeof bool !== 'boolean' ) {
+			b.fail( 'should return a boolean' );
+		}
+	}
+	b.toc();
+	if ( !isBoolean( bool ) ) {
+		b.fail( 'should return a boolean' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
+
+bench( pkg+'::objects:isObject', function benchmark( b ) {
+	var strs;
+	var bool;
+	var i;
+
+	strs = [
+		[],
+		{},
+		function noop() {},
+		new String( '' ),
+		new String( '\uDBFF' ),
+		new String( '\uDBFFFF\uDBFF' )
+	];
+
+	b.tic();
+	for ( i = 0; i < b.iterations; i++ ) {
+		bool = isWellFormedString.isObject( strs[ i % strs.length ] );
+		if ( typeof bool !== 'boolean' ) {
+			b.fail( 'should return a boolean' );
+		}
+	}
+	b.toc();
+	if ( !isBoolean( bool ) ) {
+		b.fail( 'should return a boolean' );
+	}
+	b.pass( 'benchmark finished' );
+	b.end();
+});
diff --git a/is-well-formed-string/docs/repl.txt b/is-well-formed-string/docs/repl.txt
new file mode 100644
index 00000000..cc8c6602
--- /dev/null
+++ b/is-well-formed-string/docs/repl.txt
@@ -0,0 +1,82 @@
+
+{{alias}}( str )
+    Tests if a string is well-formed.
+
+    Parameters
+    ----------
+    str: any
+        String to test.
+
+    Returns
+    -------
+    bool: boolean
+        Boolean indicating whether str is well-formed.
+
+    Examples
+    --------
+    > var bool = {{alias}}( '' )
+    true
+
+    > bool = {{alias}}( new String( '' ) )
+    true
+
+    > bool = {{alias}}( '\uDBFF' )
+    false
+
+    > bool = {{alias}}( '\uDBFFFF\uDBFF' )
+    false
+
+    > bool = {{alias}}( [] )
+    false
+
+    > bool = {{alias}}( '-5' )
+    true
+
+    > bool = {{alias}}( null )
+    false
+
+
+{{alias}}.isPrimitive( str )
+    Tests if a string is a well-formed string primitive.
+
+    Parameters
+    ----------
+    str: any
+        String to test.
+
+    Returns
+    -------
+    bool: boolean
+        Boolean indicating whether str is a well-formed string primitive.
+
+    Examples
+    --------
+    > var bool = {{alias}}.isPrimitive( '' )
+    true
+    > bool = {{alias}}.isPrimitive( new String( '' ) )
+    false
+
+
+{{alias}}.isObject( str )
+    Tests if a string is a well-formed string object.
+
+    Parameters
+    ----------
+    str: any
+        String to test.
+
+    Returns
+    -------
+    bool: boolean
+        Boolean indicating whether str is a well-formed string object.
+
+    Examples
+    --------
+    > var bool = {{alias}}.isObject( '' )
+    false
+    > bool = {{alias}}.isObject( new String( '' ) )
+    true
+
+    See Also
+    --------
+
diff --git a/is-well-formed-string/docs/types/index.d.ts b/is-well-formed-string/docs/types/index.d.ts
new file mode 100644
index 00000000..734f8ae0
--- /dev/null
+++ b/is-well-formed-string/docs/types/index.d.ts
@@ -0,0 +1,133 @@
+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+// TypeScript Version: 4.1
+
+/**
+* Interface defining `isWellFormedString` with methods for testing for primitives and objects, respectively.
+*/
+interface isWellFormedString {
+	/**
+	* Tests if a string is well-formed.
+	*
+	* @param str - string to test
+	* @returns boolean indicating whether string is well-formed
+	*
+	* @example
+	* var bool = isWellFormedString( '' );
+	* // returns true
+	*
+	* @example
+	* var bool = isWellFormedString( new String( '' ) );
+	* // returns true
+	*
+	* @example
+	* var bool = isWellFormedString( '\uDBFF' );
+	* // returns false
+	*
+	* @example
+	* var bool = isWellFormedString( '\uDBFFFF\uDBFF' );
+	* // returns false
+	*
+	* @example
+	* var bool = isWellFormedString( [] );
+	* // returns false
+	*
+	* @example
+	* var bool = isWellFormedString( '-5' );
+	* // returns true
+	*
+	* @example
+	* var bool = isWellFormedString( null );
+	* // returns false
+	*/
+	( str: any ): str is string | String;
+
+	/**
+	* Tests if a string is a well-formed string primitive.
+	*
+	* @param str - string to test
+	* @returns boolean indicating if a string is a well-formed string primitive.
+	*
+	* @example
+	* var bool = isWellFormedString.isPrimitive( '' );
+	* // returns true
+	*
+	* @example
+	* var bool = isWellFormedString.isPrimitive( new String( '' ) );
+	* // returns false
+	*/
+	isPrimitive( str: any ): str is string;
+
+	/**
+	* Tests if a string is a well-formed string object.
+	*
+	* @param str - string to test
+	* @returns boolean indicating if a string is a well-formed string object
+	*
+	* @example
+	* var bool = isWellFormedString.isObject( '' );
+	* // returns false
+	*
+	* @example
+	* var bool = isWellFormedString.isObject( new String( '' ) );
+	* // returns true
+	*/
+	isObject( str: any ): str is Object;
+}
+
+/**
+* Tests if a string is well-formed.
+*
+* @param str - string to test
+* @returns boolean indicating whether string is well-formed
+*
+* @example
+* var bool = isWellFormedString( '' );
+* // returns true
+*
+* @example
+* var bool = isWellFormedString( new String( '' ) );
+* // returns true
+*
+* @example
+* var bool = isWellFormedString( '\uDBFF' );
+* // returns false
+*
+* @example
+* var bool = isWellFormedString( '\uDBFFFF\uDBFF' );
+* // returns false
+*
+* @example
+* var bool = isWellFormedString( [] );
+* // returns false
+*
+* @example
+* var bool = isWellFormedString( '-5' );
+* // returns true
+*
+* @example
+* var bool = isWellFormedString( null );
+* // returns false
+*/
+declare var isWellFormedString: isWellFormedString;
+
+
+// EXPORTS //
+
+export = isWellFormedString;
diff --git a/is-well-formed-string/docs/types/test.ts b/is-well-formed-string/docs/types/test.ts
new file mode 100644
index 00000000..41f6f568
--- /dev/null
+++ b/is-well-formed-string/docs/types/test.ts
@@ -0,0 +1,60 @@
+/*
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+import isWellFormedString = require( './index' );
+
+
+// TESTS //
+
+// The function returns a boolean...
+{
+	isWellFormedString( '' ); // $ExpectType boolean
+	isWellFormedString( 'Hello' ); // $ExpectType boolean
+}
+
+// The compiler throws an error if the function is provided an unsupported number of arguments...
+{
+	isWellFormedString(); // $ExpectError
+	isWellFormedString( '', '\uDBFF' ); // $ExpectError
+}
+
+// Attached to main export is an isPrimitive method which returns a boolean...
+{
+	// eslint-disable-next-line no-new-wrappers
+	isWellFormedString.isPrimitive( new String( '' ) ); // $ExpectType boolean
+	isWellFormedString.isPrimitive( '' ); // $ExpectType boolean
+}
+
+// The compiler throws an error if the isPrimitive method is provided an unsupported number of arguments...
+{
+	isWellFormedString.isPrimitive(); // $ExpectError
+	isWellFormedString.isPrimitive( '', '\uDBFF' ); // $ExpectError
+}
+
+// Attached to main export is an isObject method which returns a boolean...
+{
+	// eslint-disable-next-line no-new-wrappers
+	isWellFormedString.isObject( new String( '' ) ); // $ExpectType boolean
+	isWellFormedString.isObject( '\uDBFF' ); // $ExpectType boolean
+}
+
+// The compiler throws an error if the isObject method is provided an unsupported number of arguments...
+{
+	isWellFormedString.isObject(); // $ExpectError
+	isWellFormedString.isObject( '', '\uDBFF' ); // $ExpectError
+}
diff --git a/is-well-formed-string/examples/index.js b/is-well-formed-string/examples/index.js
new file mode 100644
index 00000000..bf730ead
--- /dev/null
+++ b/is-well-formed-string/examples/index.js
@@ -0,0 +1,44 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+/* eslint-disable no-new-wrappers */
+
+'use strict';
+
+var isWellFormedString = require( './../lib' );
+
+console.log( isWellFormedString( '' ) );
+// => true
+
+console.log( isWellFormedString( new String( '' ) ) );
+// => true
+
+console.log( isWellFormedString( '\uDBFF' ) );
+// => false
+
+console.log( isWellFormedString( '\uDBFFFF\uDBFF' ) );
+// => false
+
+console.log( isWellFormedString( [] ) );
+// => false
+
+console.log( isWellFormedString( '-5' ) );
+// => true
+
+console.log( isWellFormedString( null ) );
+// => false
diff --git a/is-well-formed-string/lib/index.js b/is-well-formed-string/lib/index.js
new file mode 100644
index 00000000..6c84767b
--- /dev/null
+++ b/is-well-formed-string/lib/index.js
@@ -0,0 +1,87 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+/**
+* Test if a string is well-formed.
+*
+* @module @stdlib/assert/is-well-formed-string
+*
+* @example
+* var isWellFormedString = require( '@stdlib/assert/is-well-formed-string' );
+*
+* var bool = isWellFormedString( '' );
+* // returns true
+*
+* bool = isWellFormedString( new String( '' ) );
+* // returns true
+*
+* bool = isWellFormedString( '\uDBFF' );
+* // returns false
+*
+* bool = isWellFormedString( '\uDBFFFF\uDBFF' );
+* // returns false
+*
+* bool = isWellFormedString( [] );
+* // returns false
+*
+* bool = isWellFormedString( '-5' );
+* // returns true
+*
+* bool = isWellFormedString( null );
+* // returns false
+*
+* @example
+* // Use interface to check for well-formed string primitives...
+* var isWellFormedString = require( '@stdlib/assert/is-well-formed-string' ).isPrimitive;
+*
+* var bool = isWellFormedString( '\uDC00' );
+* // returns false
+*
+* bool = isWellFormedString( new String( '' ) );
+* // returns false
+*
+* @example
+* // Use interface to check for well-formed string objects...
+* var isWellFormedString = require( '@stdlib/assert/is-well-formed-string' ).isObject;
+*
+* var bool = isWellFormedString( '\uDC00' );
+* // returns false
+*
+* bool = isWellFormedString( new String( '' ) );
+* // returns true
+*/
+
+// MODULES //
+
+var setReadOnly = require( '@stdlib/utils/define-nonenumerable-read-only-property' );
+var main = require( './main.js' );
+var isPrimitive = require( './primitive.js' );
+var isObject = require( './object.js' );
+
+
+// MAIN //
+
+setReadOnly( main, 'isPrimitive', isPrimitive );
+setReadOnly( main, 'isObject', isObject );
+
+
+// EXPORTS //
+
+module.exports = main;
diff --git a/is-well-formed-string/lib/iswellformed.js b/is-well-formed-string/lib/iswellformed.js
new file mode 100644
index 00000000..11d01f42
--- /dev/null
+++ b/is-well-formed-string/lib/iswellformed.js
@@ -0,0 +1,79 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// VARIABLES //
+
+var RE_UTF16_LOW_SURROGATE = /[\uDC00-\uDFFF]/;
+var RE_UTF16_HIGH_SURROGATE = /[\uD800-\uDBFF]/;
+
+
+// MAIN //
+
+/**
+* Tests if a string is a well-formed string.
+*
+* @param {string} str - input string
+* @returns {boolean} boolean indicating if a value is a well-formed string primitive
+*
+* @example
+* var bool = isWellFormed( '' );
+* // returns true
+*
+* @example
+* var bool = isWellFormed( new String( '\uDC00' ) );
+* // returns false
+*/
+function isWellFormed(str) {
+	var i;
+	for ( i = 0; i < str.length; i++ ) {
+		// Checking if a low surrogate is present at the beginning
+		if ( i === 0 && RE_UTF16_LOW_SURROGATE.test(str[i]) ) {
+			return false;
+		}
+
+		// Checking if a high surrogate is present at the last position
+		if ( i === str.length - 1 && RE_UTF16_HIGH_SURROGATE.test(str[i]) ) {
+			return false;
+		}
+
+		// Checking if there is no low surrogate after a high surrogate
+		if ( i < str.length - 1 && RE_UTF16_HIGH_SURROGATE.test(str[i]) ) {
+			if ( RE_UTF16_LOW_SURROGATE.test(str[i + 1]) ) {
+				i += 1;
+			}
+			else {
+				return false;
+			}
+		}
+
+		// Checking if there is no high surrogate before a low surrogate
+		if ( i > 0 && RE_UTF16_LOW_SURROGATE.test(str[i]) ) {
+			if ( !RE_UTF16_HIGH_SURROGATE.test(str[i - 1]) ) {
+				return false;
+			}
+		}
+	}
+	return true;
+}
+
+
+// EXPORTS //
+
+module.exports = isWellFormed;
diff --git a/is-well-formed-string/lib/main.js b/is-well-formed-string/lib/main.js
new file mode 100644
index 00000000..5f4e0ec3
--- /dev/null
+++ b/is-well-formed-string/lib/main.js
@@ -0,0 +1,70 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var isPrimitive = require( './primitive.js' );
+var isObject = require( './object.js' );
+
+
+// MAIN //
+
+/**
+* Tests if a string is well-formed.
+*
+* @param {string} str - input string
+* @returns {boolean} boolean indicating whether a string is well-formed
+*
+* @example
+* var bool = isWellFormedString( '' );
+* // returns true
+*
+* @example
+* var bool = isWellFormedString( new String( '' ) );
+* // returns true
+*
+* @example
+* var bool = isWellFormedString( '\uDBFF' );
+* // returns false
+*
+* @example
+* var bool = isWellFormedString( '\uDBFFFF\uDBFF' );
+* // returns false
+*
+* @example
+* var bool = isWellFormedString( [] );
+* // returns false
+*
+* @example
+* var bool = isWellFormedString( '-5' );
+* // returns true
+*
+* @example
+* var bool = isWellFormedString( null );
+* // returns false
+*/
+function isWellFormedString( str ) {
+	return ( isPrimitive( str ) || isObject( str ) );
+}
+
+
+// EXPORTS //
+
+module.exports = isWellFormedString;
diff --git a/is-well-formed-string/lib/object.js b/is-well-formed-string/lib/object.js
new file mode 100644
index 00000000..0a85e22b
--- /dev/null
+++ b/is-well-formed-string/lib/object.js
@@ -0,0 +1,53 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var isString = require('./../../is-string');
+var isWellFormed = require('./iswellformed.js');
+
+
+// MAIN //
+
+/**
+* Tests if a string is a well-formed string object.
+*
+* @param {string} str - input string
+* @returns {boolean} boolean indicating if a string is a well-formed string object
+*
+* @example
+* var bool = isWellFormedString( '\uDC00' );
+* // returns false
+*
+* @example
+* var bool = isWellFormedString( new String( '' ) );
+* // returns true
+*/
+function isWellFormedString( str ) {
+	return (
+		isString.isObject( str ) &&
+		isWellFormed( str.valueOf() )
+	);
+}
+
+
+// EXPORTS //
+
+module.exports = isWellFormedString;
diff --git a/is-well-formed-string/lib/primitive.js b/is-well-formed-string/lib/primitive.js
new file mode 100644
index 00000000..da4e82c9
--- /dev/null
+++ b/is-well-formed-string/lib/primitive.js
@@ -0,0 +1,51 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var isWellFormed = require('./iswellformed.js');
+
+
+// MAIN //
+
+/**
+* Tests if a string is a well-formed string primitive.
+*
+* @param {string} str - input string
+* @returns {boolean} boolean indicating if a string is a well-formed string primitive
+*
+* @example
+* var bool = isWellFormedString( '\uDC00' );
+* // returns false
+*
+* @example
+* var bool = isWellFormedString( new String( '' ) );
+* // returns false
+*/
+function isWellFormedString( str ) {
+	return (
+		typeof str === 'string' && isWellFormed( str )
+	);
+}
+
+
+// EXPORTS //
+
+module.exports = isWellFormedString;
diff --git a/is-well-formed-string/package.json b/is-well-formed-string/package.json
new file mode 100644
index 00000000..f3757e85
--- /dev/null
+++ b/is-well-formed-string/package.json
@@ -0,0 +1,71 @@
+{
+  "name": "@stdlib/assert/is-well-formed-string",
+  "version": "0.0.0",
+  "description": "Test if a string is a well-formed string.",
+  "license": "Apache-2.0",
+  "author": {
+    "name": "The Stdlib Authors",
+    "url": "https://github.com/stdlib-js/stdlib/graphs/contributors"
+  },
+  "contributors": [
+    {
+      "name": "The Stdlib Authors",
+      "url": "https://github.com/stdlib-js/stdlib/graphs/contributors"
+    }
+  ],
+  "main": "./lib",
+  "directories": {
+    "benchmark": "./benchmark",
+    "doc": "./docs",
+    "example": "./examples",
+    "lib": "./lib",
+    "test": "./test"
+  },
+  "types": "./docs/types",
+  "scripts": {},
+  "homepage": "https://github.com/stdlib-js/stdlib",
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/stdlib-js/stdlib.git"
+  },
+  "bugs": {
+    "url": "https://github.com/stdlib-js/stdlib/issues"
+  },
+  "dependencies": {},
+  "devDependencies": {},
+  "engines": {
+    "node": ">=0.10.0",
+    "npm": ">2.7.0"
+  },
+  "os": [
+    "aix",
+    "darwin",
+    "freebsd",
+    "linux",
+    "macos",
+    "openbsd",
+    "sunos",
+    "win32",
+    "windows"
+  ],
+  "keywords": [
+    "stdlib",
+    "stdassert",
+    "assertion",
+    "assert",
+    "utilities",
+    "utility",
+    "utils",
+    "util",
+    "number",
+    "numeric",
+    "negative",
+    "is",
+    "isnumber",
+    "isnumeric",
+    "type",
+    "check",
+    "primitive",
+    "object"
+  ]
+}
diff --git a/is-well-formed-string/test/test.js b/is-well-formed-string/test/test.js
new file mode 100644
index 00000000..4c6566ba
--- /dev/null
+++ b/is-well-formed-string/test/test.js
@@ -0,0 +1,43 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var tape = require( 'tape' );
+var isWellFormedString = require( './../lib' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+	t.ok( true, __filename );
+	t.strictEqual( typeof isWellFormedString, 'function', 'main export is a function' );
+	t.end();
+});
+
+tape( 'attached to the main export is a method to test for a well-formed string primitive', function test( t ) {
+	t.equal( typeof isWellFormedString.isPrimitive, 'function', 'export is a function' );
+	t.end();
+});
+
+tape( 'attached to the main export is a method to test for a well-formed string object', function test( t ) {
+	t.equal( typeof isWellFormedString.isObject, 'function', 'export is a function' );
+	t.end();
+});
diff --git a/is-well-formed-string/test/test.main.js b/is-well-formed-string/test/test.main.js
new file mode 100644
index 00000000..eab84390
--- /dev/null
+++ b/is-well-formed-string/test/test.main.js
@@ -0,0 +1,61 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var tape = require( 'tape' );
+var isWellFormedString = require( './../lib/main.js' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+	t.ok( true, __filename );
+	t.strictEqual( typeof isWellFormedString, 'function', 'main export is a function' );
+	t.end();
+});
+
+tape( 'the function returns `true` if provided a well-formed string', function test( t ) {
+	t.equal( isWellFormedString( '' ), true, 'returns true' );
+	t.equal( isWellFormedString( new String( '' ) ), true, 'returns true' ); // eslint-disable-line no-new-wrappers
+	t.end();
+});
+
+tape( 'the function returns `false` if not provided a well-formed string', function test( t ) {
+	var strs;
+	var i;
+
+	strs = [
+		'5\uDBFF',
+		'\uDBFF\uDBFF',
+		'Hello \uDBFFWorld',
+		'\uDBFF',
+		'\uDBFFFFF',
+		'\uDC00\uDC00',
+		[],
+		{},
+		function noop() {}
+	];
+
+	for ( i = 0; i < strs.length; i++ ) {
+		t.equal( isWellFormedString( strs[i] ), false, 'returns false when provided '+strs[i] );
+	}
+	t.end();
+});
diff --git a/is-well-formed-string/test/test.object.js b/is-well-formed-string/test/test.object.js
new file mode 100644
index 00000000..8914b0d8
--- /dev/null
+++ b/is-well-formed-string/test/test.object.js
@@ -0,0 +1,69 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var tape = require( 'tape' );
+var isWellFormedString = require( './../lib/object.js' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+	t.ok( true, __filename );
+	t.strictEqual( typeof isWellFormedString, 'function', 'main export is a function' );
+	t.end();
+});
+
+tape( 'the function returns `true` if provided a well-formed string object', function test( t ) {
+	t.equal( isWellFormedString( new String( '' ) ), true, 'returns true' ); // eslint-disable-line no-new-wrappers
+	t.end();
+});
+
+tape( 'the function returns `false` if provided a string primitive, even if it is well-formed', function test( t ) {
+	t.equal( isWellFormedString( '' ), false, 'returns false' );
+	t.end();
+});
+
+tape( 'the function returns `false` if not provided a well-formed string', function test( t ) {
+	var strs;
+	var i;
+
+	strs = [
+		'\uDBFF',
+		new String( '\uDBFF\uDBFF' ), // eslint-disable-line no-new-wrappers
+		new String( '\uD800' ), // eslint-disable-line no-new-wrappers
+		'\uDBFFFFFF',
+		null,
+		true,
+		void 0,
+		[],
+		{},
+		new Date(),
+		/./,
+		new RegExp( '.' ), // eslint-disable-line prefer-regex-literals
+		function noop() {}
+	];
+
+	for ( i = 0; i < strs.length; i++ ) {
+		t.equal( isWellFormedString( strs[i] ), false, 'returns false when provided '+strs[i] );
+	}
+	t.end();
+});
diff --git a/is-well-formed-string/test/test.primitive.js b/is-well-formed-string/test/test.primitive.js
new file mode 100644
index 00000000..1ef40a7b
--- /dev/null
+++ b/is-well-formed-string/test/test.primitive.js
@@ -0,0 +1,66 @@
+/**
+* @license Apache-2.0
+*
+* Copyright (c) 2024 The Stdlib Authors.
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You may obtain a copy of the License at
+*
+*    http://www.apache.org/licenses/LICENSE-2.0
+*
+* Unless required by applicable law or agreed to in writing, software
+* distributed under the License is distributed on an "AS IS" BASIS,
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+* See the License for the specific language governing permissions and
+* limitations under the License.
+*/
+
+'use strict';
+
+// MODULES //
+
+var tape = require( 'tape' );
+var isWellFormedString = require( './../lib/primitive.js' );
+
+
+// TESTS //
+
+tape( 'main export is a function', function test( t ) {
+	t.ok( true, __filename );
+	t.strictEqual( typeof isWellFormedString, 'function', 'main export is a function' );
+	t.end();
+});
+
+tape( 'the function returns `true` if provided a well-formed string primitive', function test( t ) {
+	t.equal( isWellFormedString( '' ), true, 'returns true' );
+	t.end();
+});
+
+tape( 'the function returns `false` if provided a string object, even if the string is well-formed', function test( t ) {
+	t.equal( isWellFormedString( new String( '' ) ), false, 'returns false' ); // eslint-disable-line no-new-wrappers
+	t.end();
+});
+
+tape( 'the function returns `false` if not provided a well-formed string', function test( t ) {
+	var strs;
+	var i;
+
+	strs = [
+		'\uDBFFFFFF',
+		'\uD800',
+		new String( '\uDBFF' ), // eslint-disable-line no-new-wrappers
+		3.14,
+		null,
+		true,
+		void 0,
+		[],
+		{},
+		function noop() {}
+	];
+
+	for ( i = 0; i < strs.length; i++ ) {
+		t.equal( isWellFormedString( strs[i] ), false, 'returns false when provided '+strs[i] );
+	}
+	t.end();
+});