African American men who have sex with men (AAMSM) are vastly overrepresented among people with HIV/AIDS. Using data from 595 AAMSM in Philadelphia, we explored differences in sociodemographics, psychosocial characteristics related to beliefs about ethnicity, sexuality and masculinity, and sexual behavior with men and women by self-reported sexual identity (gay, bisexual, down low, straight). Roughly equivalent numbers identified as gay (40.6 %) and bisexual (41.3 %), while fewer identified as straight (7.6 %) or down low (10.5 %), with significant differences in age, income, history of incarceration, HIV status, alcohol and drug problems, childhood sexual abuse, and connection to the gay community evident among these groups. Analysis of psychosocial characteristics theorized to be related to identity and sexual behavior indicated significant differences in masculinity, homophobia, and outness as MSM. Gay and straight men appeared to be poles on a continuum of frequency of sexual behavior, with bisexual and down low men being sometimes more similar to gay men and sometimes more similar to straight men. The percentage of men having total intercourse of any kind was highest among down low and lowest among gay men. Gay men had less intercourse with women, but more receptive anal intercourse with men than the other identities. There were no significant differences by identity in frequency of condomless insertive anal intercourse with men, but gay men had significantly more condomless receptive anal intercourse. There were significant differences by identity for condomless vaginal and anal intercourse with women. This study demonstrates the importance of exploring differences in types of sex behavior for AAMSM by considering sexual identity.