Research suggests that about 30% of urban Black male adolescents report first sex younger than age 13. Considering physical and neurological development during early adolescence, a natural question is when is it too early for adolescents to have sex? Very early sex may challenge social norms and for some, suggest coercive experiences. It also challenges how parents, teachers and practitioners approach early sex education for boys. To gain a better understanding of the context of early sexual experiences, we explored partner-, personal-, and parent-level factors associated with early sex onset among Black male adolescents aged 15-24. Cross-sectional sample of male patients aged 15-24 recruited from three primary care and two STD clinics in one urban mid-Atlantic city. From 08/14-09/17, data were collected for ∼2 weeks at each clinic over five rounds. Among eligible participants, 493 enrolled (participation rate=70%) were asked about their age of first sex (outcome), demographic, sexual and reproductive health (SRH) characteristics. The last round (08/17-09/17; analytic sample n=66) also assessed contextual-level factors of the first sex experience at partner- (i.e., “much older/younger” aged partner, relationship status, sex wantedness, sex decision-making), personal- (i.e., perceived knowledge about sex, peer norms, masculinity beliefs and traits), and parent-levels (i.e., parent/guardian closeness, relationship satisfaction, and supervision, perceived parents’/guardians’ beliefs about sex). Frequencies and cross-tabs of participants’ characteristics by first sex at 13 or younger (early sex onset) versus later onset were generated. Pearson chi-squared tests were conducted to explore associations between early sex onset with participants’ characteristics and contextual-level factors. Across all rounds, 29% of males aged 15-24 reported early sex onset, which varied only by pregnancy history; a higher proportion with early onset (61%) were involved in a pregnancy than later onset (41%) (p<.001). Contextual factors at early sex onset experience included 50% of partners were hookups, 43% had “much older” partner, 57% did not want it to happen/had mixed feelings, 71% made joint decision with partner to have sex, 57% felt closer to partner, 64% had sex with partner again, 57% did not know what they were doing, and 71% held traditional masculine beliefs. Less than half felt close or satisfied with parent/guardian relationships. Partner age, perceived knowledge about sex, and parental relationships were associated with early sex onset: a higher proportion self-reported a “much older” first partner than later onset males (43% vs. 9%; p=.038) and lacked knowledge about sex (57% vs. 28%; p=.046); a lower proportion reported being close (43%) or relationship satisfaction with their maternal (50%), and paternal (31%) parent/guardian than later onset males (72%, 83%, and 68%, respectively) (p=.046, p=.013; and p=.016, respectively). Findings suggest that early sex onset among Black males is connected to lack of strong parental ties and older sexual partners playing influential roles in encouraging early sexual behavior. While young men may not be more likely to report early first sex as unwanted, their ability to make informed, autonomous decisions with older partners requires further investigation.