Happiness is a universal pursuit, and how it can be cultivated remains a central focus in psychological science. Yet prior reviews of Positive Psychological Interventions (PPIs) often merge clinical with non-clinical samples and narrow their scope to specific PPI types, making it unclear for whom PPIs are effective, to what extent, and through which pathways. This systematic review and meta-analysis examined the effectiveness of PPIs in enhancing well-being in non-clinical populations. Using the Positive Activity Model (PAM) as a guiding framework, we examined whether consistently reported person- and activity-level features moderated outcomes. Thirty-three studies (N = 9,190) met the inclusion criteria, most commonly reflective writing tasks, multi-component/self-help programmes, and strengths-based exercises; delivery was predominantly individual, online, and assigned. A random-effects meta-analysis showed significant changes in well-being from pre- to post-intervention assessments (–0.43, p < .0001). Moderator analyses indicated that geographic region significantly moderated effects, with larger improvements observed in Asian samples relative to Western regions, suggesting that cultural context may shape how positive activities are engaged with and experienced. However, inconsistent reporting of PAM features limited the ability to assess person–activity fit directly. Overall, the findings support the value of PPIs for non-clinical populations and highlight the need for greater theoretical alignment and more consistent reporting of PAM-informed features to clarify when and for whom PPIs are most effective.
Waddington et al. (2026) studied this question.