This study examined the effectiveness of an adapted 4-session HIV prevention program. Participants included 490 adolescents who participated in either the 8- or the adapted 4-session HIVEd program. Analyses to identify mean changes in HIV-related knowledge, attitudes, self-efficacy, and behavioral intentions between participants in either the 4- (n = 274) or 8-session (n = 216) programs were completed. Findings indicate participants in both programs had positive changes at post interview across all study outcomes. No significant differences in changes between participants in the 4- and 8-session programs were found except that male adolescents in the 4-session program had significantly higher mean changes in condom knowledge (p less than 0.01). The adaptation of the 8-session HIVEd program was undertaken to better reach and accommodate the needs of a high risk incarcerated adolescent population. Findings demonstrate that HIV prevention interventions for high risk populations may be successfully adapted and condensed when based on rigorously evaluated and theoretically driven programs. (Contains 3 tables.)