Research consistently highlights the benefits of instrumental music learning in young people, yet dropout rates peak during adolescence. Moreover, participation in out-of-school musical activities has been declining steadily in Quebec and worldwide. My thesis seeks to address these trends by examining motivational profiles in young musicians and by testing a motivational intervention program designed to enhance their learning experience. The project will involve two complementary phases. First, a cross-sectional survey will be administered to a large sample of young musicians (9-16 years old) enrolled in extracurricular instrument lessons, along with their teachers. This phase will aim to document learners’ motivation and their teachers’ autonomy support. Then, a quasi-experimental study will be conducted with a subsample of older respondents (13-16 years-old). Those assigned to the experimental group will be invited to join an online community of practice, which they will access via a cross-platform application under my supervision. This intervention tool will enable adolescents to share musical preferences, learning experiences, rehearsing processes, public performances, and other creative outputs. The program’s effectiveness will be assessed using a convergent mixed-methods design with two matched groups. After six months, the intervention will end and be offered to all members of the control group. Quantitative and qualitative data will be collected during and after each six-month period. They will be combined with survey results to evaluate interventions’ influence on young musicians’ motivation and psychological need satisfaction, as well as perceived creativity and reflexivity. Links between variables will also be investigated to verify current research findings. The presentation will outline the detailed intervention program, expected results, as well as report preliminary descriptive and correlational findings, if available.