Background People with intellectual disability or borderline intellectual functioning may have poorer mental health than their peers. The present authors sought to (i) estimate the risk of poorer mental health among British adults with and without intellectual impairments and (ii) estimate the extent to which any between‐group differences in mental health may reflect between‐group differences in rates of exposure to common social determinants of poorer health. Materials and Methods The present authors undertook secondary analysis of confidentialized unit records collected in Wave 3 of Understanding Society. Results British adults with intellectual impairments living in general households are at significantly increased risk of potential mental health problems than their non‐disabled peers (e.g. GHQ Caseness OR = 1.77, 95% CI (1.25–2.52), P < 0.001). Adjusting for between‐group differences in age, gender and indicators of socio‐economic position eliminated this increased risk [GHQ Caseness adjusted OR = 1.06, 95% CI (0.73–1.52), n.s]. Conclusions Our analyses are consistent with the hypothesis that the increased risk of poor mental health among people with intellectual impairments may be attributable to their poorer living conditions rather than their intellectual impairments per se. Greater attention should be given to understanding and addressing the impact of exposure to common social determinants of mental health among marginalized or vulnerable groups.