diff --git a/classes/headers/RollupHeader.php b/classes/headers/RollupHeader.php
index a00653b4..2fb328a4 100644
--- a/classes/headers/RollupHeader.php
+++ b/classes/headers/RollupHeader.php
@@ -5,6 +5,10 @@ class RollupHeader extends HeaderBase {
 			'required'=>true,
 			'type'=>'object',
 			'default'=>array()
+		),
+		'dataset'=>array(
+			'required'=>false,
+			'default'=>0
 		)
 	);
 	
@@ -12,48 +16,68 @@ public static function init($params, &$report) {
 		//make sure at least 1 column is defined
 		if(empty($params['columns'])) throw new Exception("Rollup header needs at least 1 column defined");
 		
-		//store all the rollup rows in the report
 		if(!isset($report->options['Rollup'])) $report->options['Rollup'] = array();
-		$report->options['Rollup'][] = $params;
+		
+		// If more than one dataset is defined, add the rollup header multiple times
+		if(is_array($params['dataset'])) {
+			$new_params = $params;
+			foreach($params['dataset'] as $dataset) {
+				$new_params['dataset'] = $dataset;
+				$report->options['Rollup'][] = $new_params;
+			}
+		}
+		// Otherwise, just add one rollup header
+		else {
+			$report->options['Rollup'][] = $params;
+		}
 	}
 	
-	public static function beforeRender(&$report) {
-		//cache for Twig parameters for each column
+	public static function beforeRender(&$report) {			
+		//cache for Twig parameters for each dataset/column
 		$twig_params = array();
-		foreach($report->options['Rows'] as $row) {
-			foreach($row['values'] as $value) {
-				if(!isset($twig_params[$value->key])) $twig_params[$value->key] = array('values'=>array());
-				$twig_params[$value->key]['values'][] = $value->getValue();
+		
+		// First get all the values
+		foreach($report->options['Rollup'] as $rollup) {			
+			// If we already got twig parameters for this dataset, skip it
+			if(isset($twig_params[$rollup['dataset']])) continue;
+			$twig_params[$rollup['dataset']] = array();
+			foreach($report->options['DataSets'][$rollup['dataset']]['rows'] as $row) {
+				foreach($row['values'] as $value) {
+					if(!isset($twig_params[$rollup['dataset']][$value->key])) $twig_params[$rollup['dataset']][$value->key] = array('values'=>array());
+					$twig_params[$rollup['dataset']][$value->key]['values'][] = $value->getValue();
+				}
 			}
 		}
-		foreach($twig_params as $column=>&$params) {
-			//get non-null values and sort them
-			$real_values = array_filter($params['values'],function($a) {if($a === null || $a==='') return false; return true; });
-			sort($real_values);
-			
-			$params['sum'] = array_sum($real_values);
-			$params['count'] = count($real_values);
-			$params['mean'] = $params['average'] = $params['sum'] / $params['count'];			
-			$params['median'] = ($params['count']%2)? ($real_values[$params['count']/2] + $real_values[$params['count']/2+1])/2 : $real_values[ceil($params['count']/2)];
-			$params['min'] = $real_values[0];
-			$params['max'] = $real_values[$params['count']-1];
-			
-			$devs = array();
-			foreach($real_values as $v) $devs[] = pow($v - $params['mean'], 2);
-			$params['stdev'] = sqrt(array_sum($devs) / (count($devs) - 1));
+		// Then, calculate other statistical properties
+		foreach($twig_params as $dataset=>&$tp) {
+			foreach($tp as $column=>&$params) {
+				//get non-null values and sort them
+				$real_values = array_filter($params['values'],function($a) {if($a === null || $a==='') return false; return true; });
+				sort($real_values);
+				
+				$params['sum'] = array_sum($real_values);
+				$params['count'] = count($real_values);
+				$params['mean'] = $params['average'] = $params['sum'] / $params['count'];			
+				$params['median'] = ($params['count']%2)? ($real_values[$params['count']/2] + $real_values[$params['count']/2+1])/2 : $real_values[ceil($params['count']/2)];
+				$params['min'] = $real_values[0];
+				$params['max'] = $real_values[$params['count']-1];
+				
+				$devs = array();
+				foreach($real_values as $v) $devs[] = pow($v - $params['mean'], 2);
+				$params['stdev'] = sqrt(array_sum($devs) / (count($devs) - 1));
+			}
 		}
-			
-		if(!isset($report->options['FooterRows'])) $report->options['FooterRows'] = array();
 		
 		//render each rollup row
 		foreach($report->options['Rollup'] as $rollup) {
+			if(!isset($report->options['DataSets'][$rollup['dataset']]['footer'])) $report->options['DataSets'][$rollup['dataset']]['footer'] = array();
 			$columns = $rollup['columns'];
 			$row = array(
 				'values'=>array(),
 				'rollup'=>true
 			);
 			
-			foreach($twig_params as $column=>$p) {
+			foreach($twig_params[$rollup['dataset']] as $column=>$p) {
 				if(isset($columns[$column])) {
 					$row['values'][] = new ReportValue(-1,$column,PhpReports::renderString($columns[$column],$p));
 				}
@@ -61,7 +85,7 @@ public static function beforeRender(&$report) {
 					$row['values'][] = new ReportValue(-1,$column,null);
 				}
 			}
-			$report->options['FooterRows'][] = $row;
+			$report->options['DataSets'][$rollup['dataset']]['footer'][] = $row;
 		}
 	}
 }
diff --git a/sample_reports/php/timezones_multiple.php b/sample_reports/php/timezones_multiple.php
index b83758fb..534d30ab 100644
--- a/sample_reports/php/timezones_multiple.php
+++ b/sample_reports/php/timezones_multiple.php
@@ -1,6 +1,5 @@
 <?php
 // Get All Timezones By Region
-// INCLUDE: {report: "functions.php"}
 // VARIABLE: {
 //      name: "regions",
 //      multiple: true,
@@ -9,6 +8,7 @@
 //      options: ["cdt","acst","pdt"],
 //      default: "acst"
 // }
+// ROLLUP: {columns: {Timezone: "AVERAGE", Offset: "{{mean}}"}, dataset: [0,1]}
 
 $timezone_abbreviations = DateTimeZone::listAbbreviations();
 
@@ -30,12 +30,6 @@
         );
     }
     
-    $stats = array_stats($dataset['rows'], 'Offset');
-    $dataset['rows'][] = array(
-        'Timezone'=>'AVERAGE',
-        'Offset'=>$stats['mean']
-    );
-    
     $datasets[] = $dataset;
 }