Young adult transgender men who have sex with men (TMSM) engage in sexual behaviors that place them at risk of sexually transmitted infections (STIs) including HIV. To date, no HIV and STI prevention interventions have been developed specifically for young adult TMSM. To address this gap, the current study aimed to (1) adapt a small group-based behavioral HIV prevention intervention designed for young transgender women ("LifeSkills") to address the unique HIV and STI prevention needs of young TMSM ages 18-29 years and (2) conduct a pilot evaluation of the intervention ("LifeSkills for Men"; LS4M). LS4M was carried out in an iterative approach with community input along the way, which allowed for refinement of the intervention manual and enhanced participant acceptability. A LS4M Task Force was convened to guide intervention development/adaptation and study implementation. Initially, focus groups were conducted to examine the sexual health needs, concerns, and stressors facing young TMSM (n = 12; mean age = 23.8 years; 16.7% people of color). Next, LS4M was pilot tested (n = 17; mean age = 24.3 years; 23.5% people of color) to assess acceptability with the study population and feasibility of all study procedures. Overall attendance, participation rates, and positive feedback from participants demonstrate that LS4M is highly acceptable and feasible to carry out with young TMSM. Trends in outcome measures across 4 months of follow-up suggest that participation in the intervention may improve mental health, reduce internalized stigma, and reduce HIV- and STI-related risk behaviors. Further testing of the intervention enrolling young TMSM with recent sexual risk behavior at baseline and with a control group is warranted. Lessons learned for future work with young TMSM are discussed.