HIV infection continues to rise among young men who have sex with men (YMSM). We explored whether unprotected receptive anal intercourse (URAI) occasions and partners, respectively, were associated with YMSM's (N = 194; ages 18-24) self-efficacy for safe sex with regular and casual partners. We created four self-efficacy typologies: high self-efficacy with both partner types [HRHC; N = 73(41.7 %)], high self-efficacy with regular partners but low with casual partners [HRLC; N = 24(13.7 %)], low self-efficacy with regular partners but high with casual partners [LRHC; N = 21(12.0 %)], and low with both partner types [LRLC; N = 57(32.6 %)]. YMSM in the LRHC category reported fewer URAI occasions, whereas those in the HRLC group reported more URAI partner and occasions, respectively. YMSM having serodiscordant partners were more likely to report more URAI partners, and be represented in the LRLC category. These findings underscore the importance of addressing differential self-efficacy across partner types, and highlight an urgent need to enhance YMSM's self-efficacy with casual partners.