In this study we examined differences in social support and coping between mothers of adolescents and adults with an autism spectrum disorder (ASD) in Taiwan and the United States and to investigate the effects of social support and coping strategies on family adaptation and maternal well-being. Participants were 76 Taiwanese mothers who had at least one son or daughter with an ASD (10 years old and older), and a comparison group of 325 mothers in the United States matched on the age range of the child with an ASD. Mothers completed self-administered, written questionnaires and participated in an interview. Taiwanese mothers reported significantly greater use of problem-focused and emotion-focused coping strategies than did mothers in the United States. For Taiwanese families, greater use of problem-focused coping strategies was associated with lower levels of depressive symptoms and anxiety. Emotion-focused coping mediated the relationships between ethnicity/culture and several outcome measures: family adaptability, family cohesion, and maternal depressive symptoms. The higher levels of emotion-focused coping in Taiwanese mothers appeared to account for their lower levels of family adaptability and cohesion and higher levels of maternal depressive symptoms. The results from this cross-cultural study helped determine the role of social support and coping strategies in family adaptation and maternal well-being in families of individuals with an ASD in each culture. Implications for service delivery are discussed. (Contains 5 tables and 5 figures.)