SYNOPSIS: Objective. Coparenting quality has been linked to both parenting stress and parenting self-efficacy in families of typically developing children, but little is known about relations between these factors in families where there is a child with an autism spectrum disorder (ASD). This study employed structural equation modeling to explore relations among coparenting quality, autism-specific parenting self-efficacy, and parenting stress in mothers and fathers of children with an ASD. Design. A cohort of biological mothers (n = 80) and fathers (n = 72) who were caring for their young child (age < 13) with a diagnosed ASD self-completed validated surveys assessing parenting stress, coparenting quality, and autism-specific parenting self-efficacy. Results. Both mothers and fathers reported high and similar levels of parenting stress which shared predictive relations with both coparenting quality and autism-specific parenting self-efficacy. Structural equation modeling demonstrated that the relations between perceptions of autism-specific parenting self-efficacy and parenting stress were mediated by coparenting quality. Conclusion. Coparenting quality shares an important relation with parenting stress in both mothers and fathers of children with an ASD, and enhanced perceptions of autism-specific parenting self-efficacy are unlikely to influence parenting stress when parents experience poor quality coparenting.