Objectives. We assessed the effectiveness of P4 for Women, a faith-based HIV intervention. Methods. We used a 2-arm comparative effectiveness trial involving 134 African American women aged 18 to 34 years to compare the effectiveness of the Centers for Disease Control and Prevention–defined evidence-based Sisters Informing Sisters about Topics on AIDS (SISTA) HIV intervention with P4 for Women, an adapted faith-based version of SISTA. Participants were recruited from a large black church in Atlanta, Georgia, and completed assessments at baseline and follow-up. Results. Both SISTA and P4 for Women had statistically significant effects on this study’s primary outcome—consistent condom use in the past 90 days—as well as other sexual behaviors. However, P4 for Women also had statistically significant effects on the number of weeks women were abstinent, on all psychosocial mediators, and most noteworthy, on all measures of religious social capital. Results were achieved by enhancing structural social capital through ministry participation, religious values and norms, linking trust and by reducing negative religious coping. High intervention attendance may indicate the feasibility of conducting faith-based HIV prevention research for African American women. Conclusions. P4 for Women enhanced abstinence and safer sex practices as well as religious social capital, and was more acceptable than SISTA. Such efforts may assist faith leaders in responding to the HIV epidemic in African American women.