Purpose: The aim of this study was to explore the decision-making experiences of adolescent cancer patients and their parents and siblings for medical and social decisions and appointment participation, both during and after cancer treatment. Patients and methods: Seventy semi-structured interviews were conducted with 19 adolescent cancer survivors (mean age at diagnosis = 13.3 years; average time since diagnosis = 48.6 months; mean age at interview = 16.1 years), 21 mothers, 15 fathers, and 15 siblings from 22 families. Interviews were analyzed inductively using qualitative research methodology. Emergent themes were cross-tabulated by participants' characteristics. Results: Mothers were most likely to accompany adolescents to medical appointments, especially during the post-treatment period, although fathers were eager to attend when possible. In accordance with adolescent and parent preferences, oncologists typically made major medical decisions, while families took responsibility for social and less critical medical decisions. These less critical decisions were a potential source of family conflict, particularly in relation to risk-taking behavior post-treatment. Siblings reported adopting additional decisional responsibilities, especially during their brother's or sister's treatment. Conclusion: Healthrelated decision-making within families can be difficult during adolescence, as young people assert their increasing independence. These challenges are exacerbated by a cancer diagnosis, which creates a unique paradox of legal entitlement versus parental responsibility. While adolescents and parents believe young people are entitled to be informed, they may be reluctant to assume responsibility for decisions that might affect prognosis, and report that maturity does not map well to chronological age. Attention to sibling needs is necessary to minimize the burden they carry during the family's cancer journey.