Abstract
Background Adolescence and early adulthood are critical periods for the development of health behaviours, yet longitudinal evidence on how these behaviours are socially patterned in Indonesia remains limited. Drawing on life-course theory and the social determinants of health framework, this study conceptualises Social Structure as a multidimensional construct comprising economic resources, education, family conditions, and community participation.Methods Longitudinal data from Waves 4 (2007) and 5 (2014) of the Indonesia Family Life Survey (n = 11,539) were analysed. Structural Equation Modelling was conducted across 20 multiply imputed datasets using pooled estimates to examine associations between adolescent Social Structure, health-risk behaviour in young adulthood, and behavioural change over time.Results More advantaged Social Structure was associated with lower health-risk behaviour in young adulthood (β = −0.126, p < .001) and with less adverse patterns of behavioural continuity and change between 2007 and 2014 (β = −0.142, p < .001).Conclusions Youth health-risk behaviour is socially patterned across the transition to adulthood and cannot be understood solely through individual-level explanations. They support prevention strategies that address structural inequalities alongside behavioural interventions and suggest that future research should further examine how social conditions shape behavioural trajectories across adolescence and young adulthood.