The transition to adulthood and adulthood itself have been identified as times of stress for parents of individuals with autism spectrum disorder. Longitudinal studies, however, show improvements in the well-being of mothers of adolescents and young adults with autism spectrum disorder. This article presents a cross-sectional study of 102 Spanish parents (51 mothers and 51 fathers) of 102 individuals with autism spectrum disorder. The aim was to examine parental well-being (evaluated based on stress, anxiety, depression and psychological well-being) in three groups of parents of adults, adolescents and young children with autism spectrum disorder. In addition, the relationships between parental well-being and the characteristics of their children, social support, parental age and sense of coherence were analysed. The results showed that although parental stress and psychological well-being levels were similar across the groups, depression and anxiety were lower in parents of adolescents or adults compared with parents of young children. Different factors predicted different measures of parental well-being, but sense of coherence emerged as the main predictive factor for all parental well-being measures. These findings are discussed in relation to parental adaptation over the lifespan and the implications for interventions in autism spectrum disorder families.