BackgroundOpioid use disorder (OUD) among young adults (YAs) continues to persist as a national health crisis. Best practice recommendations for YA OUD treatment highlight the importance of medication for OUD (MOUD) and family involvement across the treatment services continuum for better treatment retention and outcomes. Yet, concerned significant others (CSOs) such as family members, romantic partners, and family-of-choice members are not routinely involved in OUD and MOUD treatment for YAs. MethodWe used convenience sampling to recruit 25 YAs (ages 21 to 36) in treatment for OUD from two urban treatment centers. We discussed with YAs the identities of their CSOs and the dynamics of those relationships, their perspectives on CSO involvement in their OUD treatment, and the beliefs and attitudes they hold about family involvement in treatment and recovery. Thematic content analysis was deductive-dominant based on a semi-structured qualitative interview guide. Group consensus coding was followed by matrix analysis. ResultsWe identified five main themes: (1) YA and CSO relationships were supportive, evolving, and complex. (2) CSO support motivated treatment engagement and participation. (3) Only a small proportion of CSOs participated in treatment activities despite actively supporting treatment in other ways. (4) YAs experienced their CSOs as supportive of their treatment and recovery goals, including MOUD. (5) YAs believed family involvement is essential to treatment and many were unsatisfied with current family involvement in their care. ConclusionsIn this qualitative study of OUD treatment experiences among YAs, we learned that many YAs have CSOs who are invested in their treatment and recovery and yet are not routinely involved in treatment. Moreover, YAs often expressed family involvement is essential to OUD treatment, and many expressed a desire for greater family involvement in their own treatment. Clinical recommendations for relationship-oriented treatment are presented.