Triple P is a parenting program intended to prevent and to provide treatment for severe behavioral, emotional, and developmental problems in children. The aim of this meta-analysis was to assess the effectiveness of Triple P Level 4 interventions on parenting styles and parental competency. Level 4 is an intensive training program of 8 - 10 sessions for parents of children with more severe behavioral difficulties. The results indicated that the Triple P Level 4 interventions reduced dysfunctional parenting styles in parents and also improved parental competency. These effects were maintained well through time and appear to support the widespread adoption and implementation of Triple P Level 4 interventions that is taking place in an increasing number of countries around the world. © 2008 by the National Council on Family Relations.