Numerous studies indicate interparental conflict causes child externalizing behavior. However, far less is known about the inverse relationship. Exploring this gap in the literature has clear implications for parents of children with externalizing disorders (e.g., attention-deficit/hyperactivity disorder [ADHD]). Adapting an experimental child behavior manipulation paradigm (Lang, Pelham, Atkeson, & Murphy, 1999; Pelham et al., 1997, 1998), parent couples of 9- to 12-year-old boys and girls with ADHD (n = 51) and without ADHD (n = 39) were randomly assigned to interact with a "disruptive" or "typical" confederate child. According to parent and observer ratings, parents interacting with disruptive confederates communicated less positively and more negatively with each other during and after the interactions than did parents who interacted with typical confederates. Observational coding also indicated that child effects on negative interparental communication were more noticeable among parents of youth with ADHD, particularly those with comorbid oppositional defiant disorder or conduct disorder, compared with parents of youth without ADHD. These findings extend results of prospective studies highlighting child effects on marital quality.