In this sexually transmitted infection (STI) prevention study, we compared the efficacy of the Well Woman Program (WWP), a nurse practitioner-directed, culturally specific, intensive intervention, to minimal intervention (MI), brief lecture, and referral to usual care, in a community-based randomized controlled trial. African American women having past STIs and residing in high-risk communities were randomly assigned to the two groups. STI outcome was measured at baseline and three later points. A random effects logistic longitudinal regression model showed that, at baseline, approximately 75% of participants tested positive for an STI, predominantly trichomoniasis. At month 15, the estimated probability of a WWP participant having an STI was 20% less than an MI participant. Better STI outcomes were due to the intensive individualized intervention.