Culturally relevant prevention programs are required to reduce HIV risk exposure of Latino young men who have sex with men (YMSM). As part of Hermanos Jóvenes, 465 Latino YMSM were surveyed at community venues of New York City outside the gay-identified area of lower Manhattan. We examined factors that influence ethnic and gay community attachments; the association between community attachments and social support in sexual matters; and the relationship between levels of attachment, social support in sexual matters, and sexual risk behaviors. Sixty-eight percent felt closely connected to their ethnic community; about 34% were highly attached to both neighborhood and New York City gay communities. Greater social support in sexual matters was associated with ethnic and gay community attachments. Latino YMSM connected to their ethnic community were about 40% less likely to report recent unprotected anal intercourse (UAI) with a male partner, and 60% less likely to have engaged in UAI during the last sexual contact with a nonmain male partner. Gay community attachment was not significantly related to risk behaviors. Findings point to the importance of ethnic ties and involving ethnic community organizations in HIV prevention efforts.