Families of 97 children with early-onset conduct problems, 4 to 8 years old, were randomly assigned to 1 of 4 conditions: a parent training treatment group (PT), a child training group (CT), a combined child and parent training group (CT + PT), or a waiting-list control group (CON). Posttreatment assessments indicated that all 3 treatment conditions had resulted in significant improvements in comparison with controls. Comparisons of the 3 treatment conditions indicated that CT and CT + PT children showed significant improvements in problem solving as well as conflict management skills, as measured by observations of their interactions with a best friend; differences among treatment conditions on these measures consistently favored the CT condition over the PT condition. As for parent and child behavior at home, PT and CT + PT parents and children had significantly more positive interactions, compared with CT parents and children. One-year follow-up assessments indicated that all the significant changes noted immediately posttreatment had been maintained over time. Moreover, child conduct problems at home had significantly lessened over time. Analyses of the clinical significance of the results suggested that the combined CT + PT condition produced the most significant improvements in child behavior at 1-year follow-up.