Regular HIV testing is an essential component of the HIV prevention and care cascade. Sexual minority males (SMM) account for most new HIV infections in the US and testing rates among SMM vary substantially across the lifespan. Research has largely overlooked the developmental context of HIV testing. The current study compared correlates of HIV testing among adolescents (aged 13-17; n = 1,641), emerging adults (aged 18-29; n = 50,483), early adults (aged 30-39; n = 25,830), middle adults (aged 40-64; n = 25,326), and late adults (65 and older; n = 1,452) who were recruited online. Overall, HIV testing rates were lowest among adolescent SMM. Having condomless anal sex in the past 3-months was a consistentpredictor of HIV testing across all age cohorts.The association between relationship status and frequency of HIV testing varied across ages. Being in a non-monogamous relationship (versus single) was associated with more frequent HIV testing among adolescent and emerging adult SMM , while being in a monogamous relationship (versus single) was associated with lower odds of HIV testing among early, middle, and late adults.