Objective: This study examines the effects of parental stimulant medication treatment on parent ratings of parent-child functioning. Ratings of parent-child functioning in the home setting and immediately following a laboratory-based parent-child interaction were collected. Method: Participants were 20 parents who along with their children (ages 5-12 years) were diagnosed with Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) attention-deficit/hyperactivity disorder (ADHD). Parents completed an open-label titration to determine their optimal dose of lisdexamfetamine (30, 50, or 70 mg/day) and then completed a month-long double-blind randomized pharmacological intervention for parental ADHD. Effects of parental stimulant medication administered for an extended duration were assessed by parent ratings of parent-child functioning in the home setting and immediately following a laboratory parent-child interaction task conducted at an academic mental health center. Data were collected from September 2010 to June 2013. Results: Stimulant medication versus placebo was associated with larger reductions in parental ADHD (d = 1.01-1.09), impairment (d = 0.67-0.82), and executive dysfunction (d = 0.74-0.94) in the home setting. No significant benefits of stimulant medication emerged in measures of parenting or child behavior at home. In the laboratory setting, parents treated with stimulant medication versus placebo reported fewer ADHD symptoms (d = 1.01-1.05) and their interaction was more successful (d = 0.83) and pleasant (d = 0.92). Several additional trends emerged showing beneficial effects of stimulant medication on parent-child functioning. Conclusion: Parents treated with stimulant medication evidenced some improvements in parent-child functioning, which support the use of pharmacological intervention to improve functioning in families with parent-child ADHD.