Objective Over 50% of released prisoners are reincarcerated within 3 years. Social support from loved ones postincarceration significantly reduces the likelihood of reincarceration. Increasingly, intervention developers aim to implement interventions that will enhance the stability of support available. This study responds to gaps in knowledge. Method The current efficacy study reports findings from a randomized controlled trial (n = 57) of a social support intervention. A priori power analysis indicated moderate effect sizes could be detected. Participants were men, average age was 25 years, and over 90% were African American. Preliminary effects on social support, cognitions, substance use, and rearrest were assessed. Recruitment and consent occurred in prison; the intervention and 4 follow‐ups occurred postrelease. Results Findings converge with research indicating declines in social support (b = −.70, p < .05) and perceived quality of support (b = .05, p < .01) over time. Age showed inverse relationships with support (b = −1.77, p < .05). There were no statistically significant group effects for social support, cognitions, substance use (with the exception of marijuana), or recidivism. Clinical implications are discussed. Conclusion This study advances research on intervention dosage, potency, and measurement considerations.