Traditional Korean American discipline is characterized by a lack of expression of affection and use of harsh discipline. The purpose of this study was to pilot test the effect of the Incredible Years Parenting Program among Korean American mothers. A randomized controlled experimental study design was used; 29 first-generation Korean American mothers of young children (3-8 years old) were randomly assigned to intervention (n=20) and control (n=9) groups. Intervention group mothers received a 12-week parenting program. Control group mothers did not receive the intervention. Mothers reported on discipline styles (positive, appropriate, and harsh), level of acculturation, and their child's outcomes (behavioral problems and social competence) at pre-, post-, and 1-year follow-up intervals. After completing the program, intervention group mothers significantly increased use of positive discipline as compared to control group mothers. Among intervention group mothers, high-acculturated mothers significantly increased appropriate discipline whereas low-acculturated mothers significantly decreased harsh discipline. In the 1-year follow-up, intervention group mothers maintained the significant effect for positive discipline. Providing this program appears to be a promising way of promoting positive discipline among Korean American mothers.