Abstract
Contemporary education increasingly emphasises the development of Social and Emotional Learning (SEL) competencies alongside academic achievement, recognising their importance for students’ well-being, interpersonal relationships, and lifelong success. Project-Based Learning (PBL) is frequently presented as a pedagogical approach capable of fostering these competencies through collaboration, active engagement, and authentic learning experiences. However, empirical evidence regarding the extent to which these socio-emotional benefits emerge through participation in project work remains inconclusive. This study examined changes in students’ self-perceived socio-emotional competencies following participation in PBL intervention in secondary education. A one-group pre-test–post-test pre-experimental design was employed with 38 students aged 12–14 from a public secondary school in Andalusia, Spain. Students participated in four interdisciplinary PBL projects, each comprising approximately 10–12 sessions and implemented across the first two terms of the 2024–2025 academic year. Self-perceived SEL competencies were assessed using the 30-item Social and Emotional Learning Scale, and data were analysed using Wilcoxon signed-rank tests, Mann–Whitney U tests and Spearman’s rank correlations. No statistically significant pre-test–post-test differences were detected in self-awareness, social awareness, relationship skills, or responsible decision making. Self-control showed a statistically significant decrease in the individual Wilcoxon analysis, with a moderate effect size. No statistically significant gender differences were detected in the magnitude of change. The five competencies were positively associated at both measurement points, although these analyses did not test whether the correlational pattern remained unchanged over time. Rather than questioning the socio-emotional potential of PBL, these findings challenge assumptions regarding the automatic emergence of measurable SEL gains through project participation alone. They highlight the need for further controlled research into the pedagogical conditions under which PBL may support socio-emotional development, including intentional SEL integration, teacher preparation, structured collaborative scaffolding, and performance-based assessment.