Disclosure of HIV status to potential and current sex partners by HIV-positive people (HIVPP) is a complex issue that has received a significant amount of attention. Research has found that disclosure depends upon the evaluation by HIVPP of potential benefits and risks, especially of the risks stemming from the profound social stigma of HIV and AIDS. Drawing on concepts from Goffman's classic stigma theory and Anderson's more recently developed cultural-identity theory of drug abuse, we analyzed data from in-depth, post-intervention qualitative interviews with 116 heterosexually active, HIV-positive injection drug users enrolled in a randomized trial of a behavioral intervention to prevent HIV transmission. We explored how disclosure experiences lead to "identity impacts" defined as: (1) identity challenges (i.e. interactions that challenge an individual's self-concept as a "normal" or non-deviant individual); and (2) identity transformations (i.e. processes whereby an individual comes to embrace a new identity and reject behaviors and values of an old one, resulting in the conscious adoption of a social and/or public identity as an HIV-positive individual). Participants engaged in several strategies to manage the identity impacts associated with disclosure. Implications of these findings for research and prevention programming are discussed.