The article focuses on a key aspect of the experiences of young gay men and considers how their responses might inform HIV prevention education for all young people. The article first outlines key representations of same-sex desire and of HIV/AIDS through which young gay men learn various certainties about gay men, gay sex and AIDS. As a consequence of these certainties many young men--before they come out--develop an unwavering commitment to condom use. The article goes on to describe how this commitment is problematic as the one and only discourse of protection that they use, and may be "counterproductive" in terms of protecting themselves and others from HIV. The third section of the article focuses on three sets of uncertainties--about sexual identity, about AIDS risks, and about condom use in relationships--and posits a deconstructive approach to HIV prevention which would be helpful to the whole school population. (Contains 2 notes.)