Objective: To examine the follow-up effectiveness of brief parent training (BPT) for children with emerging or existing conduct problems. Method: With the use of a randomized controlled trial and parent and teacher reports, this study examined the effectiveness of BPT compared to regular services 6 months after the end of the intervention. Participants included 216 children (3–12 years) and parents randomly assigned to BPT or a comparison group. Results: BPT had beneficial effects on caregiver assessments of parenting practices (i.e., positive parenting and harsh discipline) and child conduct problems in the families 6 months after the intervention. The effects of BPT in schools and day care centers were limited. Compared to posttest the effects sizes were smaller and number of significant effects lower. Conclusion: Although effects decreased over time, this study demonstrate that a short-term manual-based intervention (3–5 sessions) could be effective in reducing conduct problems 6 month after the intervention.