<p>This study presents the results of evaluating the pilot implementation of the Lions Quest programme “Skills for Action” (LQSFAc) in the Croatian education system. “Skills for Action” is a prevention programme for social-emotional learning based on the Collaborative for Academic, Social and Emotional Learning framework. This model encompasses intrapersonal, interpersonal, and cognitive aspects of social-emotional well-being that are important at all stages of development. This is the first attempt to evaluate the LQSFAc programme in Croatia, focusing on its outcomes. The aim of the study is to analyse the extent to which the two-year pilot implementation of the programme contributes to the development of students’ intrapersonal and interpersonal social-emotional skills. A questionnaire for self-assessment of students’ social-emotional skills was used. The programme was introduced on a trial basis in 13 Croatian secondary schools during the 2023/2024 and 2024/2025 school years. This quasi-experimental study includes quantitative data from 326 students who participated in the pre- and post-test (163 students participated in the programme and 163 did not). The data were analysed using descriptive statistics and a multilevel model (mixed linear model with a random effect for the school where the programme was implemented). Students in the LQSFAc classes achieved higher scores in all analysed social-emotional skills in the post-test than students in the comparison classes. The results suggest that the contribution of the LQSFAc programme is most evident in students’ social awareness. Implementing the LQSFAc programme in full, which requires a whole-school approach, is essential for achieving better results.</p>