This 5-year study aims to understand determinants that perpetuate and mitigate stigma toward anal sex during healthcare encounters, in order to develop and pilot a strategy that responds to these determinants and thereby improves the quality of care and HIV service engagement among men who have sex with men (MSM). The study team collected data during in-depth interviews with 20 adult MSM as well as 20 adult healthcare workers (HCWs) to identify strategies that could be readily used in health services to reduce stigma. Analysis of this data then informed consultation with an advisory board of HCWs and healthcare consumers (not limited to MSM), to develop the content of a set of implementation strategies to mitigate stigma and thereby improve health service delivery. Evaluation of a set of implementation strategies was performed in the Southern US, a high incidence region, by pilot testing with 65 adult HCWs who in clinical sites where MSM are under-engaged in HIV services.