Background: The aim of this study was to evaluate the Parents Plus Adolescents Programme (PPAP)-a parent training course specifically targeting parents of young adolescents (aged 11-16 years)-when delivered as a preventative programme in community school settings. Methods: A sample of 126 parents (mean age of children = 12.34 years; range = 10-16 years) were randomly assigned to either a treatment (PPAP; n = 82) or a waiting-list control condition (WC; n = 44). Analyses are based on a study-completer sample post-treatment (n = 109 parents: PPAP n = 70; WC n = 39) and sample at 6 month follow up (n = 42 parents). Results: Both post-treatment (between groups) and 6-month follow-up comparisons of study completers (within PPAP group) revealed significant positive effects of the parenting intervention with respect to adolescent behaviour problems and parenting stress. The post treatment comparisons demonstrated large effect sizes on global measures of child difficulties (partial eta squared = 0.15) and self-reported parent stress (partial eta squared = 0.22); there was a moderate effect size on the self-reported parent satisfaction (partial eta squared = 0.13). Conclusions: This study provides preliminary evidence that PPAP may be an effective model of parent-training implemented in a community-based setting. The strengths and limitations of the study are discussed.