Objective: To assess the impact of a campus community health worker program (HealthPALs) on student influenza vaccination. Participants: Undergraduate students at a northeastern US university (enrollment 6650), influenza seasons 2011-2012 through 2015-2016. Methods: Study design: Difference-in-differences analysis of student vaccination at campus dormitory influenza clinics during intervention vs. baseline. Intervention: In the first intervention year, HealthPALs conducted in-person peer outreach at several campus dormitory flu clinics. Subsequent years, HealthPALs conducted an enhanced intervention, with the addition of a personalized, dormitory-specific social media campaign appealing to students' community identity. Results: The initial intervention increased vaccinations by 66% (IRR = 1.66, 95%CI 1.39-1.97) at intervention clinics relative to control. The enhanced intervention increased vaccinations by 85% (IRR = 1.85, 95%CI 1.75-1.96).Conclusion: Community health workers can be a highly effective, low-cost strategy for increasing influenza vaccination among college students. This model could also be used to address other campus health challenges where student engagement is key.