Background: Adolescent substance use can place youth at risk of a range of poor outcomes. Few studies have attempted to explore in-depth young people's perceptions of how familial processes and dynamics influence adolescent substance use. Objectives: This article aimed to explore risk and protective factors for youth substance use within the context of the family with a view to informing family based interventions. Methods: Nine focus groups supplemented with participatory techniques were facilitated with a purposive sample of sixty-two young people (age 13–17 years) from post-primary schools across Northern Ireland. The data were transcribed verbatim and analyzed using thematic analysis. Results: Three themes emerged from the data: (1) parent-child attachments, (2) parenting style, and (3) parental and sibling substance misuse. Parent-child attachment was identified as an important factor in protecting adolescents from substance use in addition to effective parenting particularly an authoritative style supplemented with parental monitoring and strong parent-child communication to encourage child disclosure. Family substance use was considered to impact on children's substance use if exposed at an early age and the harms associated with parental substance misuse were discussed in detail. Both parent and child gender differences were cross-cutting themes. Conclusion: Parenting programmes (tailored to mothers and fathers) may benefit young people via components on authoritative styles, parental monitoring, communication, nurturing attachments and parent-child conflict. Youth living with more complex issues, e.g., parental substance misuse, may benefit from programmes delivered beyond the family environment, e.g., school based settings.