When a child is diagnosed with an autism spectrum disorder (ASD) parents often experience a range of difficult feelings, which typically are not addressed in child-focused interventions. This study examined the relationship between a mother's acceptance of and sense of resolution regarding her child's diagnosis of an ASD and maternal interaction style, controlling for child competence, autism symptoms and maternal depression. Participants included 63 children with an ASD between 20 and 50 months of age and their mothers. Mothers who were more emotionally resolved were rated as higher in Cognitive Engagement and Supportive Engagement in play interactions, reflecting greater verbal and nonverbal scaffolding to enhance the child's play and attention to activities and greater reciprocity and mutual enjoyment. This study highlights the importance of considering a mother's resolution about her child's diagnosis, suggesting that maternal emotions and cognitions associated with the diagnosis may be potential targets for intervention.