The purpose of this study was to examine how parental homework completion, session attendance, and treatment knowledge influenced parenting practices and confidence in using learned skills during behavioral parent training (BPT). Parents of 54 preschoolers (Mage = 5.07, 82% Hispanic/Latino) with externalizing behavior problems participated in an 8-week group BPT program. Pre-and posttreatment measures included parent-reported parenting practices and a treatment knowledge quiz. Parental homework completion, or home practice of skills, was reported by parents and collected weekly. Increases in positive parenting and decreases in negative parenting were observed (Cohen’s d = .63 and .70, respectively), as well as increases in treatment knowledge (d = 1.46). Treatment knowledge moderated the association between parental homework completion and negative parenting as well as parenting skill-use confidence. Increased parental homework completion was only associated with decreases in negative parenting and increa...