Antunes, RodrigoBaumeister, HaraldPryss, RüdigerKüchler, Ann-MarieKraft, RobinBerghoff, NilsNagel, LuziaReichert, ManfredIdrees, Abdul RahmanStach, MichaelMelchior, MariaDavisse-Paturet, CamilleFalkiner, Emmavan der Waerden, JudithBaban, AdrianaTaut, DianaDanila, IngridPerez Anton, MarionaPorricelli, DanieleSanguesa, JuliaMoneta, María VictoriaGarcía Carrión, RocíoFinkenauer, CatrinGonneke StevensKrabbendam, LydiaBolinski, FelixMaresova, PetraNilsen, PerKarlsson, NadineMoreno, NataliaLe Corvec, AnaïsHaro, Josep Maria2026-05-252026-05-252026-04-28Lima, R. A., Baumeister, H., Pryss, R., Küchler, A.-M., Kraft, R., Berghoff, N., Nagel, L., Reichert, M., Idrees, A. R., Stach, M., Melchior, M., Davisse-Paturet, C., Falkiner, E., van der Waerden, J., Baban, A., Taut, D., Danila, I., Perez-Anton, M., Porricelli, D., et al. (2026). Study protocol of the e-Intervention Enhancing Mental Health in Adolescents (IMPROVA) project: a randomised controlled trial to promote adolescents” mental health and well-being in four European countries. BMJ open, 16(4), e108674. https://doi.org/10.1136/BMJOPEN-2025-10867410.1136/BMJOPEN-2025-108674https://hdl.handle.net/20.500.14454/6061INTRODUCTION: This trial aims to evaluate the impact of the IMPROVA intervention programme in improving mental health, quality of life, and well-being in adolescents enrolled in secondary schools in four European countries. METHODS AND ANALYSIS: The IMPROVA intervention will be evaluated using a two-arm parallel group pragmatic cluster randomised controlled trial with an intervention and a wait-list control group. Secondary schools in France, Germany, Romania, and Spain were recruited. Originally, we estimated to enrol a total of 6000 students within 64 schools; that is, 16 schools per country. The IMPROVA programme is a multi-level intervention that provides tailored content for adolescents, families, and school staff. This content creates a unified and supportive framework that promotes mental health and social-emotional development among adolescents. A series of implementation strategies was planned to support the uptake of the programme into the education setting and among participants. Study outcomes were assessed at baseline, mid-term (during the intervention), postintervention (primary end point), and will be assessed at postintervention (secondary end-point; 6 months after postintervention). Overall mental health (Strengths and Difficulties Questionnaire) is the primary outcome. Secondary outcomes include: health-related quality of life, depression, anxiety, social isolation, and self-esteem. The trial will be evaluated regarding its effectiveness, cost-effectiveness, implementation, and social return on investment analysis. ETHICS AND DISSEMINATION: This study has received the approval of human research ethics committees in France (Comité de Protection des Personnes Ile-de-France VIII", No. 2024-A00201-46), Germany (Ulm University Ethics Committee, No. 186-24), Romania (The Research Ethics Subcommittee of the Babeș-Bolyai University of Cluj-Napoca, No. 14.146/23.09.2024), and Spain (CEIm Fundació Sant Joan de Déu, No. PIC-61-24). Results will be disseminated through peer-reviewed open-access publications and presentations at national and international conferences. Non-technical summaries will be shared with public health authorities, participants, and stakeholder organisations. All findings will be reported in aggregate form, ensuring no individual participant can be identified.eng© Author(s) (or their employer(s)) 2026AdolescentsCommunity child healthEHealthMENTAL HEALTHPsychosocial Interventionjournal article2026-05-252044-6055