Fathers, in general, have been underrepresented in studies of parent training outcome for children with attention deficit hyperactivity disorder (ADHD), and the present study aimed to investigate the efficacy of a behavioral parent training program developed expressly for fathers. The present investigation randomly assigned 55 fathers of children ages 6 to 12 with ADHD to the Coaching Our Acting-out Children: Heightening Essential Skills (COACHES) program or a waitlist control group. Outcomes for the study included objective observations of parent behaviors and parent ratings of child behavior. Results indicated that fathers in the COACHES group reduced their rates of negative talk and increased rates of praise as measured in parent-child observations, and father ratings of the intensity of problem behaviors were reduced, relative to the waitlist condition. Groups did not differ on observations of use of commands or father ratings of child behavior problems. Untreated mothers did not significantly improve on observational measures or behavioral ratings. This study provides preliminary evidence for the efficacy of the COACHES parenting program for fathers of children with ADHD. Results are cast in light of the larger literature on behavioral parent training for ADHD as well as how to best work with fathers of children with ADHD in treatment contexts. (Contains 4 tables, 1 figure and 1 footnote.)