Objectives: To examine college peer crowd affiliations and prosocial and risky behaviors (academic, sexual, drug, and alcohol related risks) as well as to investigate gender as a moderator of these relations. Participants: 527 students at a public university in the Midwest in Fall 2018 (M age = 19.67, SD = 1.84). Method: Students' peer crowd affiliations were reported using an online survey. Four peer crowd dimensions were confirmed using Factor Analysis: Social (popular partiers and Greek organization members), Athletic, Arts/Diverse (students identifying strongly with a countercultural group, their race/ethnic group, and/or performing arts); and Scholastic (academic achievement and leadership). Results: Social crowd affiliations positively predicted all risk-related behaviors. Social and Scholastic affiliations positively predicted prosocial behaviors. Finally, gender significantly moderated the relations between peer crowd affiliations and risk and prosociality. Conclusions: These findings demonstrate that peer crowd affiliation and gender are important when promoting positive behaviors on campus.