Compared to the parents of typically developing children, the parents of children with ADHD are likelier to engage in lower rates of positive and higher rates of negative parenting behavior. However, relatively few studies have tested process-oriented models explaining why such deficits in parenting are common among the parents of children with ADHD. With a sample of 107 mothers and their adolescent children with ADHD, the current study tested the hypothesis that the difficulties associated with an adolescent's ADHD predicted greater parenting-related stress, which in turn would be associated with problems in parenting behavior. Using a structural equation modelling approach, we tested a model in which mothers' parenting stress mediated the relationship between potentially stressful difficulties associated with an adolescent's ADHD (i.e., adolescents' metacognitive and self-regulatory problems, mothers' depressive symptoms) and parenting behavior (i.e., warmth, use of psychological control). We tested three variations of this model with different measures of maternal parenting stress (global evaluative stress, stress due to feelings of guilt, and stress about children's academic achievement). The model in which global stress mediated the relationship between factors associated with ADHD and parenting behavior had excellent fit and all paths were significant. Other measures of stress resulted in models with weaker fit, but these models were nonetheless informative and are discussed in further detail.