Across Canada, the rate of sexually transmitted infections (STIs) among gay, bisexual, and other men who have sex with men (gbMSM) has significantly increased. Public health officials have suggested that the increasing STI rates are a result of decreasing condom use, motivated by the utilization of biomedical HIV treatment and prevention strategies (henceforth: biomedical strategies), like Pre-Exposure Prophylaxis (PrEP) and Post-Exposure Prophylais (PEP). However, our understanding of associations between gbMSM’s biomedical strategies, condom use behaviors, and STIs is limited because: 1) research has yet to assess how individual, interpersonal, and social factors shape the relationship between gbMSM’s biomedical strategy choices and condom use, and 2) research has yet to confirm that gbMSM’s biomedical strategies shape condom use choices in ways that actually predict a subsequent STI. My research will address these limitations by analyzing the rich and exciting data of the Engage Study, a four-year long Canadian study of gbMSM’s sexual health and behaviors (see: https://www.engage-men.ca/). This research will inform newer, more effective STI interventions for gbMSM that incorporate sexual health practices of the modern age.