Substance use disorders (SUDs) in adolescence have negative long-term health effects, which can be mitigated through successful treatment. Caregivers play a central role in adolescent treatment involvement; however, studies have not examined treatment motivation and pressures to enter treatment in caregiver/adolescent dyads. Research suggests that internally motivated treatment (in contrast to coerced treatment) tends to lead to better outcomes. We used Self-determination theory (SDT) to examine intersecting motivational narratives among caregivers and adolescents in SUD treatment. Relationships between motivation, interpretation of caregiver pressures, adolescent autonomy, and relatedness were also explored. Adolescents in SUD treatment and their caregivers (N-Dyads = 15) were interviewed about treatment experiences. Interviews were coded for treatment motivation, including extrinsic (e.g., motivated by punishment), introjected (e.g., motivated by guilt), and identified/integrated motivation (e.g., seeing a behavior as integral to the self). Internalization of treatment motivation, autonomy support/competence (e.g., caregiver support for adolescent decisions), and relatedness (e.g., acceptance and support) were also coded. Four dyadic categories were identified: agreement that treatment was motivated by the adolescent (intrinsic); agreement that treatment was motivated by the caregiver (extrinsic); agreement that treatment was motivated by both, or a shift towards adolescent control (mixed/transitional); and disagreement (adolescents and caregivers each claimed they motivated treatment; conflicting). Autonomy support and relatedness were most prominent in intrinsic dyads, and least prominent in extrinsic dyads. The mixed/transitional group was also high in autonomy support and relatedness. The extrinsic group characterized caregiver rules as an unwelcome mechanism for behavioral control; caregivers in the other groups saw rules as a way to build adolescent competence and repair relationships, and adolescents saw rules as indicating care rather than control. Adolescents with intrinsic motivations were the most engaged in treatment. Results suggest the importance of intrinsically motivated treatment, and highlight autonomy support and relatedness as mechanisms that might facilitate treatment engagement. (C) 2017 Elsevier Inc. All rights reserved.