The effectiveness of implementation intentions in children: A systematic review and meta-analysis

Self-regulation abilities in childhood are important for long-term academic achievement and healthy development. As self-regulatory abilities are still developing, 'simple' interventions are needed to foster self-regulation. Implementation intentions are simple plans that could promote goal achievement in children. However, little is known about their overall effectiveness and moderating factors in children. This registered report presents a systematic review of the literature and a meta-analysis of the effects of implementation intentions on children's goal achievement. The meta-analysis included a total of 52 effect sizes from 42 studies (N = 12,957, M_age = 10.67 years), published between 1975 and 2025. Overall, we found a small-to-medium effect of implementation intentions in children (Hedge's g = 0.31, 95% CI [0.21; 0.41]). Study heterogeneity was high (Q(51) = 146.47, p < .001, I² = 65.2%). The effects were stronger in studies with younger children and (in some analyses) children with ADHD, suggesting that implementation intentions are particularly effective when self-regulation abilities are limited. Future research should increase conceptual and methodological rigour. In addition, research and practice should aim to support children in forming strong mental representations of plans, generating high-quality plans themselves and using implementation intentions as a meta-strategy.