From happiness to meaning: a systematic review of quantitative research on core constructs in positive psychology

BackgroundSince its formal inception in 1998, positive psychology has generated a rich and rapidly expanding empirical literature centred on constructs such as happiness, meaning, flourishing, hope, gratitude, resilience, character strengths, flow, and self-determination. Despite this proliferation, the construct landscape remains fragmented, with inconsistent operationalization, overlapping measurement frameworks, and unresolved theoretical tensions between hedonic and eudaimonic accounts of well-being.ObjectiveThis systematic review aims to map and synthesize the empirical evidence base underpinning core constructs in positive psychology research, evaluate the theoretical relationships among constructs, assess methodological quality, and identify priority directions for future inquiry.MethodsThis review is restricted to peer-reviewed quantitative empirical studies (randomised controlled trials, quasi-experimental designs, longitudinal cohort studies, and cross-sectional studies with validated instruments); qualitative empirical studies and purely philosophical or theoretical works were excluded. A systematic search of PubMed, PsycINFO, Web of Science, Scopus, and Cochrane CENTRAL was conducted for peer-reviewed studies published between January 2000 and April 2025. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), 2020 guidelines informed the review protocol. Seventy-one primary studies and fifteen meta-analyses met all inclusion criteria.ResultsFindings reveal robust but construct-specific evidence bases. Hedonic well-being (happiness, positive affect, life satisfaction) and eudaimonic well-being (meaning, purpose, engagement) demonstrated the strongest and most replicated evidence. Gratitude, hope, character strengths, and resilience showed consistently positive effects across diverse populations. Emerging constructs including digital well-being, AI-mediated meaning-making, and gamification-enhanced engagement demonstrated nascent but promising evidence bases. Significant methodological limitations were identified including construct proliferation, measurement heterogeneity, and Western, Educated, Industrialized, Rich, and Democratic (WEIRD) sampling bias.ConclusionThe positive psychology construct landscape is scientifically substantive yet theoretically fragmented. Integrative frameworks, cross-cultural validation, and technology-informed delivery represent the most critical future priorities.