Sexually transmitted infections (STIs)—including HIV, syphilis, gonorrhea, chlamydia, and certain types of human papillomavirus (HPV) which cause anogenital and oral cancers—pose a heavy burden on population health. Disadvantaged people are disproportionately affected and may face health-access barriers that further concentrate STIs within high-risk networks and amplify transmission. This is particularly true for gay, bisexual, and other men who have sex with men and people living with HIV/AIDS. In keeping with the World Health Organization’s vision to end STI epidemics, complications and deaths and with the Public Health Agency of Canada’s pan-Canadian framework for action to reduce health impacts of HIV/ STIs, the goal of the ESTIMATE lab is to generate evidence for effective, efficient, and practical strategies to prevent STIs and STI-related cancers in communities at higher risk.