The present study tested whether parents caring for children with developmental disabilities would have higher blood pressure compared to parents of typically developing children (controls). It also examined the psychosocial factors underlying this observation. Thirty-five parents of children with developmental disability and thirty controls completed standard measures of perceived stress, child challenging behaviours and social support and wore an ambulatory blood pressure (BP) monitor throughout the day, for one day. Relative to controls, parents caring for children with developmental disabilities reported poorer psychosocial functioning and had a higher mean systolic BP. Of the psychosocial predictors, only social support was found to be predictive. Moreover, variations in social support accounted for some of the between group differences with the [beta] for parental group attenuated from 0.42 to 0.34 in regression analyses. It appears that social support may influence blood pressure responses in parental caregivers. Finally, our findings underscore the importance of providing psychosocial interventions to improve the health of family caregivers. (Contains 3 tables and 1 figure.)