A program of cognitive-behavioral therapy with aggressive children (so called ‘Training mit aggressiven Kindern’) is a well established cognitive-behavioral treatment for aggressive children aged about 6-12 years. The latest version of the ‘Training mit aggressiven Kindern’ (Petermann & Petermann, 2005) was conducted with 13 children diagnosed with conduct disorder or oppositional defiant disorder at an education counselling center in North Rhine-Westphalia in Germany. The participants were 7-13 years old and intervention lasted 4 months. A follow-up was conducted 6 months later. A pre-post comparison of parent ratings on the Child Behavior Checklist (CBCL) and the Strengths and Difficulties Questionnaire (SDQ) documented an improvement in oppositional defiant and aggressive behavior, lower rates of hyperactive behavior, and fewer problems with peers. Results confirm a long-term efficacy of the ‘Training mit aggressiven Kindern’.