Abstract
This thesis examines the relationship between identity, social belonging, and alcohol and other drug (AoD) use among adolescents and emerging adults in Aotearoa New Zealand. Grounded in Identity Control Theory (ICT) and extended through the Identity Transformation Framework (ITF), the research investigates how identity processes contribute to both the maintenance of substance use and pathways to recovery.
A mixed-methods approach was employed across three studies. Study 1 analysed treatment outcomes among young people engaged in AoD services, examining associations between belonging and wellbeing within a therapeutic context. Findings indicated that belonging was associated with wellbeing outcomes, although the pattern was complex and appeared particularly shaped by gender. Study 2 used a three-wave longitudinal design within a first-year university residential sample to examine relationships between belonging, wellbeing, and alcohol-related risk. The exploratory observed-variable cross-lagged analyses suggested reciprocal associations between belonging and wellbeing, rather than a simple one-directional pathway. However, the findings did not show that belonging independently predicted lower later alcohol-related risk after accounting for baseline AUDIT and covariates. Study 3 utilised online Social Identity Mapping (oSIM) and qualitative analysis to explore how emerging adults with a history of substance use, construct and navigate multiple social identities within this context. Thematic analysis identified key identity domains, including support systems, academic and professional identity, and community belonging, with group memberships differing in their encouragement or discouragement of AoD use.
Across studies, findings demonstrate that identity-related processes, particularly social belonging and group identification, play a central role in shaping substance use trajectories. While identity was not directly measured, belonging functioned as an observable proxy for identity processes across quantitative and qualitative contexts. The results are interpreted as supporting the utility of ICT and ITF in understanding substance use as embedded within social identity systems, rather than solely individual behaviour.
This thesis contributes to theory by integrating sociological and psychological perspectives on identity, and to practice by highlighting the importance of identity-focused and socially embedded interventions. In the context of Aotearoa New Zealand, these findings underscore the need for culturally responsive approaches that account for the intersection of identity, belonging, and systemic inequities in shaping youth substance use and recovery.