Online dating apps have become a central part of the dating market over the past decade, yet their broader effects remain unclear. We analyze the impact of Tinder, the pioneer and market leader in the dating app space, on a segment of the population that was among the earliest adopters of this technology: college students. For identification, we rely on the fact that Tinder's initial marketing strategy centered on Greek organizations (fraternities and sororities) within college campuses. Using a comprehensive survey containing more than 1.1 million responses, we estimate a difference-in-differences model comparing student outcomes before and after Tinder's full-scale launch and across students' membership in Greek organizations. We show that Tinder's introduction led to a sharp, persistent increase in the frequency of sexual activity, but with no corresponding impact on the likelihood of relationship formation. Inequality in dating outcomes increased among male students but not among female students. Further, we observe a rise in the incidences of sexual assaults and sexually transmitted diseases. However, despite these changes, Tinder's introduction did not worsen students' mental health and may have even led to improvements for female students. These results suggest that the transformation of dating due to dating apps has far-reaching and nuanced effects on young adults.