SCIREARLY implemented all planned scientific activities, achieving its objectives through systematic reviews, quantitative and qualitative research, comparative policy analysis, quasi-experimental designs, and co-creation. The project first established an evidence base on the social determinants of underachievement and early school leaving (WP1). A systematic literature review demonstrated that underachievement and ESL result from the interaction of multiple factors rather than single causes. It showed that practices such as grade repetition are associated with negative academic and well-being outcomes, while inclusive, dialogic, and community-engaged approaches support learning and belonging. SCIREARLY analysed policy approaches in Europe that have successfully reduced ESL rates, identifying key features of effective prevention-oriented strategies. Recognising the critical role of early childhood education and care, SCIREARLY advanced scientific knowledge on ECEC quality and its long-term impact (WP2). A comprehensive scoping review showed that high-quality ECEC environments combining relational, emotional, and cognitively stimulating practices have lasting positive effects on educational trajectories. Based on this evidence, the project developed indicators of ECEC quality and piloted a Self-Assessment ECEC Quality Instrument. A large-scale European survey involving practitioners from 18 countries identified core dimensions of ECEC quality, highlighting strengths and areas for improvement such as family engagement and professional development. These findings were complemented by focus groups with children, families, and staff, resulting in a co-created framework defining essential features of high-quality ECEC. SCIREARLY also identified and analysed Successful Learning Environments in compulsory education (WP3). Through 20 in-depth case studies across 11 countries, the project showed that effective learning environments integrate academic learning and well-being through inclusive and relational practices, supported by strong leadership, high expectations, personalised support, and professional collaboration. A quasi-experimental study tested the transferability and scalability of these practices in schools across Europe, demonstrating positive effects on learning outcomes and student well-being, particularly in primary education (WP4). Using a life-course approach, SCIREARLY explored educational trajectories of learners from vulnerable backgrounds who succeeded against the odds (WP5) and identified key drivers of success, including sustained relational support, inclusive school climates, mentoring, peer relationships, and personal agency, highlighting the importance of integrated academic, social, and emotional support. Finally, an integrated, evidence-based framework translateed complex research results into an actionable structure for policy, research, and practice. Finally, the SCIREARLY Impact Platform, an open-access resource, ensures the long-term usability of the project’s outcomes (WP6).