Background: Few population-based studies have examined the association between disability and personal wellbeing (PWB) among working-age adults. Objective/Hypothesis: To determine: (1) the magnitude of differences in wellbeing between working-age adults with and without disability in contemporary samples representative of the UK population; and (2) whether the size of any observed differences between people with and without disability is moderated by age, gender, ethnicity, partnership status, educational attainment or employment status. Methods: Secondary analysis of data from three national cross-sectional surveys. Results: In each survey, people with disability scored lower than people without disability on all four indicators of PWB. Adjusting for the main effects of potentially moderating variables reduced the effect size of disability on PWB by an average of 24%. Subsequently adjusting for the two-way interaction terms between disability and potentially moderating variables reduced the effect size of disability (main effect) on PWB by an additional average of 73%. PWB among people with disability was significantly lower for: (1) men; (2) younger people; (3) those who belong to the majority ethnic group (white British); (4) those without a partner; and (5) people with lower socio-economic position. Conclusions: Our findings indicate that demographic characteristics and exposure to specific social determinants of poor health play a major role in the negative association between disability and personal wellbeing. A more sophisticated understanding of how social determinants interact to produce inequities associated with identities such as disability, gender, race, sexuality, and class (intersectionality) can inform effective policy interventions.