Behaviour parent training (BPT) is known to effectively reduce child externalising problems. However, evidence for BPT to have secondary benefits for reducing internalising symptoms remains unclear. To address this, electronic databases (PsycINFO, MEDLINE, EMBASE, CINAHL, and SCOPUS) were systematically searched for studies examining internalising outcomes from BPT among children aged 2-12 years with clinically elevated externalizing problems. Outcomes for internalising problems following BPT were analysed by meta-analysis. Of 9105 studies identified, 24 studies met the eligibility criteria. Results from meta-analysis demonstrated a significant small treatment effect size (g���=���- 0.41) for reducing internalising symptoms immediately after treatment. Studies showed moderate heterogeneity (I���=���44%). Moderation analyses indicated that the overall treatment effect was robust against variations in treatment and study design characteristics. However, a review of individual study methods indicate that these results are limited by significant heterogeneity and limitations in clinical assessment. Overall, the results suggest that BPT programmes for reducing externalising problems have the potential to improve internalising outcomes, but that there is limited information to determine the reliability of these effects, highlighting the need for further investigation.
