Parenting responsiveness and over-reactivity were assessed among 25 mothers of 7-9-year-old sons with Attention-Deficit/Hyperactivity Disorder (ADHD) and oppositional behavior (Oppositional Defiant, OD), 24 mothers of sons with ADHD only, and 38 mothers of nonproblem sons. Responsiveness was observed during mother-son play and clean-up interactions and over-reactivity was assessed using self-reports of parenting in discipline situations. Mothers of sons with ADHD/OD were less responsive and more over-reactive than mothers of nonproblem sons, and mothers of sons with ADHD only did not differ from the other groups. Mothers of sons with ADHD/OD reported more hostility than mothers of nonproblem sons, and controlling for maternal hostility eliminated the significant group differences in responsiveness during clean-up and in over-reactivity. Controlling for the child's ADHD subtype did not alter the pattern of results. The implications for addressing responsiveness and over-reactivity as components of parent-mediated behavioral treatments for ADHD are considered.KEY WORDS: ADHD; oppositional behavior; mother-child interactions; responsiveness.