The psychological well-being of fathers of children with developmental disabilities remains poorly understood. The present study examined depressive symptoms, pessimism, and coping in fathers of adolescents and young adults with Down syndrome (DS;n = 59), autism spectrum disorders (ASDs;n = 135), and Fragile X syndrome (n = 46). Fathers of sons or daughters with ASDs reported a higher level of depressive symptoms than the other groups of fathers. Fathers of sons or daughters with DS reported a lower level of pessimism than the other groups of fathers. There were no group differences in paternal coping style. Group differences in paternal depressive symptoms and pessimism were, in part, related to differences in paternal age, the child's behavior problems, risk of having additional children with a disability, and maternal depressive symptoms. Findings from this study can be used to educate providers and design services for fathers during the later parenting years.