Minority women, incarcerated women, and women using drugs or engaged in survival sex are most vulnerable to HIV. This pilot study was designed to estimate efficacy of an intervention, Women First!, to help these women correctly and consistently use male condoms. Women (N = 74) were recruited from jails, substance-abuse treatment centers, and public health clinics, and enrolled in a randomized controlled trial with an attentiononly comparison group. The intervention, based on social cognitive theory and the theory of gender and power and awakening, was delivered over 6 weeks; unprotected vaginal intercourse and correct condom use were measured before and after the intervention. Changes on the dependent variables did not rise to statistical significance due to low power, but descriptive statistics and the multivariate partial η2 effect size estimate of 0.27 suggest that Women First! is a promising intervention. Future research will require improvements in recruitment, retention, and measurement.