This study examines leading explanations for unsafe sex in light of in-depth interviews with 102 high-risk gay and bisexual men in Toronto to see how well they engage with the social circumstances and reasoning processes of men in their sexual relationships. We argue that there is an inadequate fit between some of the leading explanations and the discursive accounts provided by high risk men themselves. Their accounts focus on unsafe sex occurring as a resolution to condom and erectile difficulties, through momentary lapses and trade offs, out of personal turmoil and depression, and as a byproduct of strategies of disclosure and intuiting safety. This study examines, in particular the circumstances and rationales associated with men who identify their practices as "barebacking." We conclude with recommendations for communicating prevention messages to those most at risk based on the self-understandings of gay and bisexual men who most frequently practice unprotected sex.