Originally identified in homosexual men, HIV increasingly affects others, including injection drug users, noninjection drug users who engaged in unsafe sex, and non-drug-using heterosexuals who engage in high-risk sexual behavior. Many HIV interventions have lacked sound theoretical frameworks, although some attempts have been made to ground HIV risk behavior interventions in such behavior theories as the health belief model, cognitive social learning theory, the theory of reasoned action, and the transtheoretical model of behavior change (TMBC). An HIV prevention intervention developed from the TMBC model hypothesizing stages of change was evaluated using injection drug users, crack cocaine users, and their female sexual partners. Stage of change was identified, and participants received an intervention based on their stage. Baseline and post-intervention follow-up data were obtained on participant perceived stage and reported HIV sexual risk behavior. Data showed there was little congruence between perceived stage and reported risk. Despite this incongruence, significant decreases in HIV risk behavior were observed. 20 references and 3 tables