MIC-DROP is a CDC funded multi-site study that aims to evaluate current trends in characteristics of MSM (Men who have Sex with Men) at risk of acquiring HIV, behaviors and preferences for using PrEP products, and development and testing of prevention messages, and characterizing typologies of current and potential PrEP users with identification of prevention protection gaps. MIC-DROP will utilize a prospective cohort study design and enroll 1,275 MSM in Atlanta, Chicago and San Diego. Measurements will include HIV and STI testing, baseline and quarterly follow-up surveys over 2 years. A subgroup of participants will be invited to participate in in-depth interviews (IDI) every 6 months (up to 15 per city). The same individuals will participate in 3 IDIs. We will invite a separate group of individuals to participate in focus-group discussions (up to 50 per city, once during the study period).