Young men who have sex with men (YMSM) are disproportionately infected with HIV/AIDS and there are few prevention programs with published efficacy for this population. This study evaluated the feasibility, acceptability, and preliminary efficacy of an online, interactive, and highly engaging HIV prevention program called Keep It Up! The intervention was designed to be delivered to diverse YMSM upon receiving an HIV negative text result, with the goal for them to "Keep It Up" and stay negative. In a randomized clinical trial, the intervention was compared to an online didactic HIV knowledge condition. The study sample included 102 sexually active YMSM. Participants reported completing online modules in settings that were private and not distracting. Mixed methods data showed intervention participants felt the program was valuable and acceptable. Compared to the control condition, participants in the intervention arm had a 44 % lower rate of unprotected anal sex acts at the 12-week follow-up (p < 0.05).