This study examined how perceived sociocultural factors influenced the relationship between psychosocial variables and sexually transmitted infections (STIs) among gay men. A cross-sectional brief street-intercept survey was administered to 594 gay men. Analyses examined how well stigma, concealment and symptoms of depression explained variation in participants' histories of STIs. Results suggested that concealment partially mediated the relationship between stigma and depression and depression partially mediated the relationship between concealment and STIs. Controlling for sociodemographic factors, symptoms of depression explained more varied histories of STIs; however, concealment was negatively related to STIs. Implications for STI and HIV interventions are discussed.