In the present study, the scaling up of Parent Management Training, Oregon Model (PMTO) in Norway was examined by investigating how large-scale dissemination affected the composition of the target group and the service providers by comparing child behavioral outcomes in the effectiveness and dissemination phases of implementation. Despite the larger heterogeneity of the service providers and the intake characteristics of the target group, which are contrary to the expectations that were derived from the literature, no attenuation of program effects was detected when scaling up PMTO. In Norway, a long-term-funded centralized center, combined with an active implementation strategy, seems to have affected the quality of PMTO delivered system-wide in services for children with behavior problems.

In the present study, the scaling up of Parent Management Training, Oregon Model (PMTO) in Norway was examined by investigating how large-scale dissemination affected the composition of the target group and the service providers by comparing child behavioral outcomes in the effectiveness and dissemination phases of implementation. Despite the larger heterogeneity of the service providers and the intake characteristics of the target group, which are contrary to the expectations that were derived from the literature, no attenuation of program effects was detected when scaling up PMTO. In Norway, a long-termfunded centralized center, combined with an active implementation strategy, seems to have affected the quality of PMTO delivered system-wide in services for children with behavior problems.