Results of this review indicate that early family/parent training (EFPT) is an effective intervention for reducing behavior problems among young children. Such programs appear to have few negative effects and some clear benefits for it subjects. The overall findings lend support for the continued use of EFPT to prevent behavior problems such as antisocial behavior and delinquency. It is recommended that future research should be designed to test the main theories of the effects of EFPT. Based on evidence that early antisocial behavior is a key risk factor for continued delinquency and crime throughout the life course, EFPT has been advanced as an important intervention/prevention effort. EFPT-programs are intended to serve many purposes, one of them being the prevention of behavior problems. EFPT-programs constitute a set of methods for reducing children’s behavioral problems and later delinquency that for some time have been the focus of increasing attention. The main objective of this review is to assess the available research evidence on the effects of EFPT on child behavior problems including antisocial behavior and delinquency. In addition, to assess the overall impact of early EFPT, the review will also investigate in which settings and under what conditions it is most effective. Tables, figure, references, and appendix