The aim of this study was to examine whether the relationship between maternal psychological well-being and behavior problems in children with an autism spectrum disorder (ASD) is bidirectional. Data were available at 9 months, 3 years, and 5 years old for 132 children with ASD, identified from a population-representative sample of UK children. Three-wave cross-lagged models examined reciprocal effects between child behavior and maternal well-being (psychological distress, physical health functioning, and life satisfaction). Results indicated that the relationships between maternal well-being and child problem behaviors were not bidirectional. Specifically, findings suggested that while early behavior problems are not a risk factor for later maternal well-being, maternal psychological distress, physical health limitations, and lower life satisfaction are risk factors for later child behavior problems.