The present study evaluated the effectiveness of a parent training and emotion socialization program designed specifically for hyperactive preschoolers. Participants were 31 preschool-aged children whose parents were randomly assigned to a parent training (PT) or waitlist (WL) control group. PT parents took part in a 14-week parenting program that involved teaching parenting strategies for managing hyperactive and disruptive behavior as well as emotion socialization strategies for improving children's emotion regulation. Compared to WL mothers, PT mothers reported significantly less child inattention, hyperactivity, oppositional defiance, and emotional lability; were observed using significantly more positive and less negative parenting; and reported significantly less maternal verbosity and unsupportive emotion socialization practices. Results provide some support for the effectiveness of this parenting program for reducing attention-deficit hyperactivity disorder (ADHD) symptoms and associated problems in preschool-aged children. (Contains 5 tables and 1 figure.)