The BeHuman project was implemented with young people experiencing social vulnerability to promote social inclusion, human development, and leadership through sport and educational mentoring. The study employed a single-group pre-experimental design with a pre-test scale, complemented by qualitative interviews with participating educators. Instruments included a values questionnaire adapted from the Hall–Tonna model and a semi-structured interview with the mentors. The sample consisted of 14 adolescents (mean age = 14.29 ± 1.59 years) and three educator-mentors. Quantitative findings showed a shift in participants’ values from security and belonging (Stages I–II) towards initiative and relationship (Stage III), which correspond to more autonomous and collaborative leadership profiles in the Hall–Tonna framework. Responsibility, creativity, and loyalty values most frequently selected by the adolescents emerged as central to achieving the objectives of Stage III, focused on vocational development and the emergence of constructive leadership. Qualitatively, empathy, trust, and responsibility appeared as key mediators, shaping both mentors’ leadership practices and the development of leadership capacities among the young people. The findings support the interpretation of sport as an axiological mediator and a “laboratory of citizenship”, where structured value-based pedagogy and intentional mentoring accelerate socio-emotional maturation and foster the transfer of values such as respect, cooperation, justice, and inclusive leadership to everyday contexts. In conclusion, the Hall–Tonna model proved useful for interpreting these axiological and leadership-related transitions, and the BeHuman approach offers a replicable framework for values-based social inclusion and youth leadership development .