To date, most research with families who have a child with developmental disabilities hasbeen undertaken in English speaking countries. Poorer health, allied with increased levelsof stress has been commonly reported for mothers but less is known about the impact onfathers and on overall family functioning. This study aimed to document the correlates ofthese parental impacts with Iranian mothers and fathers who had children with eitherintellectual disabilities (ID) or with autism spectrum disorders (ASD). In all 121 parents(69 mothers and 52 fathers from 94 families) who had a child with a diagnosis of ADS,along with 115 parents of children with ID (83 mothers and 32 fathers from 101 families)volunteered to take part in the study. Each participant completed through interviewstandardised rating scales of parenting stress, emotional well-being, family functioningand satisfaction with caring role along with demographic information and details ofinformal supports. Structural Equation Modeling identified that family functioning wasmuch poorer in families whose child had ASD and both mothers and fathers reportedhigher levels of stress. Poorer emotional well-being contributed to higher stress and wasmore frequent among mothers, single parents and those whose children had behaviourproblems. Having other dependents living at home and more sources of informal supportimproved the emotional wellbeing of parents but not their stress or family functioning.Parents who derived greater satisfaction from their caring role tended to have betteremotional health and less stress. Although the impact on Iranian parents of having a childwith developmental disabilities is broadly similar to those of parents in other cultures,there are indications that children with ASD present distinct challenges to these families.The model derived in this study is a useful guide both for further research as well as familycentred interventions.