A replication of a preventive early childhood intervention study for reducing relational and physical aggression and peer victimization was conducted (Ostrov et al., 2009). The present study expanded on the original 6-week program, and the revised Early Childhood Friendship Project (ECFP) 8-week program consisted of developmentally appropriate puppet shows, active participatory activities, passive activities, and in vivo reinforcement periods. Both teacher and observer reports were obtained at pretest and posttest for relational and physical bullying, as well as relational and physical peer victimization, for each participating child. The initial sample (N = 141; age [mean] = 45.53 months; age SD = 7.29) included 80 children randomly assigned to the intervention group (six classrooms) and 61 children randomly assigned to the control group (six classrooms). The present study found that the ECFP reduced relational bullying in the intervention group relative to the control group and reduced relational and physical victimization for girls in the intervention group relative to the control group. The importance of early intervention and implications for educators and clinicians are discussed. (author abstract)