The study compared the different patterns of stress reported by mothers of children with either a chronic physical illness (cystic fibrosis), a chronic psychological disorder (autism), and children without a physical or psychological disorder. Twenty-four mothers from each of these three groups completed the Questionnaire on Resources and Stress Short Form (Holroyd & Guthrie, 1986). Each clinical group exhibited different patterns of stressful response consistent with the nature of the disorder and the requirements of care imposed on the families. Autism was found to contribute significantly more to family stress than did cystic fibrosis. The number of children in the family was not a significant variable. Implications for the development of family intervention programs are discussed.