Mechanisms of change: Exploratory outcomes from a randomised controlled trial of acceptance and commitment therapy for anxious adolescents

•Exploratory multiple mediation analyses from an RCT of ACT for adolescent anxiety.•Limited support for the full hexaflex model in mediating therapeutic outcomes.•Mixed specific effects observed for defusion, acceptance and mindfulness/self-as-context.•In contrast to predictions, mediation effects were predominantly treatment-common.•Despite their differences ACT and CBT may be underpinned by analogous mechanisms.