This study experimentally tested proximal outcomes of Connecting, a low-cost, self-directed, family-based substance-use prevention program for foster families. Families (n = 220) fostering youth age 11 to 15 years were recruited and randomly assigned into the self-administered program with telephone support (n = 110) or a treatment as usual, control condition (n = 110). Program materials included a workbook with family activities and DVDs with video clips. Survey data were collected from youth and their caregivers at baseline and 4 months later. Results indicate 60% were 'very satisfied' with Connecting, and 85% would recommend Connecting to other caregivers. Analyses revealed foster youth in the program (n = 93) were significantly more likely than controls (n = 104) to report improved problem-solving skills (Cohen's d = .13, p = .02), involvement in making family rules (OR = 2.6, p = .02), and caregiver recognition for positive behavior (OR = 3.8, p = .03) at posttest. Improvement was observed in youth report of intervention-specific communications (B = 0.15, p = 0.07) and improved refusal skills (OR = 2.09, p = .06). No significant effects were found on bonding communication, inconsistent discipline, family conflict, monitoring, and antisocial norms about substance use and violence, nor were there significant effects from any caregiver reports on similar measures. This evidence suggests that a self-administered family-focused preventive intervention can positively influence known risk and protective factors for youth in foster care.