A systematic review informing recommendations for assessing implementation variability in universal, school-based social and emotional learning interventions

There is theoretical support for, and emerging empirical evidence that, implementation variability (e.g., fidelity, dosage, quality) influences outcomes of school-based social-emotional learning (SEL) interventions, yet this relationship remains underexplored. This review aimed to (1) examine the relationship between SEL implementation variability and student outcomes and (2) identify and assess the quality of the methods used to establish this relationship, to reduce the research-to-practice gap and advance evidence-based practice. Methods. British Education Index, ERIC, PsycINFO, ASSIA, ScienceDirect, and Web of Science were searched, initially identifying 2,987 studies. A quality appraisal checklist was developed to assess the quality of research statistically examining the implementation-outcomes relationship. Extracted data were grouped according to the implementation dimension(s) assessed, the outcome domain(s) examined, and the statistical method(s) used. Results. Thirty-one studies met the review inclusion criteria. Quality assessment classified fourteen studies (45%) as low quality, fifteen (48%) as medium quality, and 2 (7%) as high quality. The most frequently examined implementation dimensions were dosage (n=16), fidelity (n=12), quality (n=10), responsiveness (n=6) and reach (n=3). Inferring the relationship between implementation variability and outcomes was hindered by the poor quality of studies and the heterogeneity, complexity, and resulting small sample size of comparison groups; calculation of meta-aggregative effect sizes was therefore not possible. Discussion. This review reveals the paucity of high-quality research examining the relationship between SEL implementation variability and student outcomes. Accordingly, we propose the use of the aforementioned quality appraisal checklist to support and guide future research in this area, alongside recommendations to advance implementation science.