Background: Approximately 75% of adolescents who receive substance abuse treatment relapse within 1 year; therefore, it is important to have effective, easily accessible aftercare resources to support them while they are in recovery. Objective: The goal of this study was twofold: (1) to find out from adolescents and counselors if an online relapse prevention program was feasible and of interest and (2) to solicit ideas for content for this program regarding peer relationships during early recovery. Methods: Sixteen counselors were interviewed about peer relationship-related content and features this program should include then asked to sort and rate the responses using an online concept mapping program. The development of an interactive prototype of the proposed program was informed by these results. This prototype was shown to the 16 counselors and 24 adolescents in substance abuse treatment (M age = 15.8 years) for feedback. Then the adolescents participated in focus groups in which they discussed their use of technology and peer relationship-related challenges in recovery. Results: The concepts that were rated highest by counselors were Setting Boundaries in Peer Relationships (M = 4.38), How to Follow Through with Decisions (M = 4.23), and Figuring Out What You Really Want (M = 4.18). Pre-established criteria for satisfaction were exceeded with both adolescents (M = 84%) and counselors (M = 86%). In the focus groups, adolescents said that they would be interested in using technology to meet challenges in recovery. Conclusions: The online relapse prevention program concept has feasibility according to these key stakeholders.