The current study investigated the moderating role of mother and father autonomy support in the link between youth Attention-Deficit Hyperactivity Disorder (ADHD) symptoms and task perseverance. ADHD symptomatology was assessed using a multi-informant composite of mother, father, and teacher ratings, and youth perseverance and parental support of autonomy were examined using a behavioral observation paradigm (i.e., difficult puzzle task). Results indicated that youth who were rated as exhibiting more symptoms of ADHD persevered less on a difficult puzzle task and that this relationship was moderated by parental level of autonomy support. In the context of high parental autonomy support, the negative relation between ADHD and perseverance became nonsignificant. Findings indicate that supporting youth autonomy may have significant implications for their development and that it would be valuable to aid parents in developing the appropriate skills necessary for them to successfully support their child's autonomy.