Background: The community-wide implementation of evidence-based programs to prevent child behavior problems could be a promising approach to reach many families. It is yet unclear whether such a behavior prevention approach could effectively improve child mental health at a population-level in Germany. Aim: Following an area-wide implementation of (universal) prevention programs in a German city, can we determine positive changes in behavior problems and quality of life of children aged 3-12 years? Method: Three programs were implemented in a community (intervention city). A randomly selected sample of families from the general population of families living in the intervention city and in a comparison city were assessed before implementation of the programs as well as 1 and 2 years later. Results: Univariate two-way between-groups analyses of variance showed no interaction effect between the cities and assessments with regard to child behavior problems and quality of life. The risk of reporting child behavior problems and living in the intervention city (contrast: comparison city) was higher at baseline (OR = 1.84) than 2 years later (OR = 0.78). Conclusion: We were not able to demonstrate clear population-level effects.