This longitudinal study examined the transactional relations between parenting stress and both internalizing and externalizing behavioral problems in young children with autism spectrum disorder (ASD) over 1.5 years using a cross-lagged panel analysis. Participants included 75 young children with ASD (Time 1; mean age = 25.68 months) and their parents. Parenting stress that was related to parent's perceptions on child characteristics was found to predict externalizing behavioral problems in young children with ASD across two time points. However, behavioral problems in young children with ASD did not predict parenting stress. These findings provide implications for early intervention and family services for young children with ASD and their families.