Little is known regarding the social and sexual behavior of bisexual men, a population of increasing importance given their risk for HIV transmission. In this exploratory study, we described a sample of 105 self‐identified bisexual men recruited through a newspaper ad and interviewed in person. Our objectives were to (a) describe their social characteristics and reported sexual behavior with males and females; (b) assess rates of disclosure of sexuality to others, including female sexual partners; (c) examine behavioral versus self‐labeling definitions of bisexuality, vis‐a‐vis involvement in the gay community, mental health, and HIV‐risk behavior; and (d) test the stability of sexual orientation during one year in a subsample of respondents. HIV‐risk behavior was generally low. Most respondents had not disclosed their same‐sex attraction to their social networks, including female sexual partners. Behaviorally bisexual men had higher psychological well‐being and lower HIV risk than did men who self‐identified as bisexual but did not meet a behavioral criterion. Among respondents recontacted one year after the original interview, 40% had changed toward a more homosexual self‐identity. We present these data for heuristic purposes in the hope that other researchers will pursue issues that are raised, and we caution against generalizing from this limited sample to larger populations.