Bullying can have serious physical and emotional consequences. In recent years, interest in this phenomenon has been growing, becoming a public health problem in the first world. The aim of this study was to evaluate the effects of the Action for Neutralization of Bullying Program (ANA) in Spanish children. This study used a quasi-experimental design that included a pre-test evaluation, 2 months of intervention, a post-test, and 3 months of follow-up. A sample of 330 children aged 7–12 years (M = 9.27; SD = 1.09) from third to sixth grade participated in the study. One hundred and fifty-nine were girls (48.2%). The program consisted of eight group sessions in which empathy, assertiveness, communication skills, conflict resolution, and group cohesion were worked on. The results showed statistically significant reductions in verbal abuse behaviors (t = 4.76, p < 0.001), direct social exclusion (t = 3.53, p < 0.001), threats (t = 2.04, p = 0.042), aggression with objects (t = 3.21, p < 0.001), and physical abuse (t = 4.41, p < 0.001). The differences were not statistically significant for indirect social exclusion behaviors (t = 1.86, p = 0.065) or cyberbullying (t = 0.31, p = 0.756). The effects in the reduction of the bullying behaviors decreased after the implementation of the program, achieving even greater reduction in victimization behaviors after 3 months than immediately after the end of the program. These results indicate that the ANA program is effective in reducing bullying behaviors in a group of children. Implications for practice and future research are discussed.