In line with growing interest in subjective well-being (SWB) as a goal of public policy, a substantial research base examining the correlates, effects and determinants of adolescent SWB is beginning to develop. However, there is a dearth of data on the SWB of adolescents with disabilities. The limited available data suggest that adolescents with disabilities in high-income countries face a heightened risk of poorer SWB relative to peers without disabilities. Few studies have investigated potential causes of disability-based differences in adolescent SWB. This lack of research may be due, in part, to the widely held but now contested assumption that disability is inherently negative and therefore a direct cause of poorer SWB. Utilising data from the Canadian National Longitudinal Survey of Children and Youth, this study investigated the potential mediating role of adverse life conditions, including socioeconomic disadvantage, impoverished peer relationships, and peer victimisation. Employing structural equation modelling, the study found evidence consistent with a causal chain running from early childhood disability, through adverse life conditions, to poorer adolescent SWB. The findings suggest that poorer SWB in adolescents with disabilities cannot be assumed or attributed to disability in any straightforward way. With equivalent means, including economic and social resources, adolescents with disabilities may enjoy levels of SWB that are not significantly different from their peers without disabilities.