Background <p>Together For Us (T4Us) is a newly developed and evidence-informed social identity intervention for youth sport. Drawing on theoretical underpinnings of social identity theory and previous shared leadership intervention research in sport, T4Us leverages athlete leaders to foster a shared sense of social identity within the team.</p> Methods <p>The purpose of this study was to conduct an initial feasibility study (Study 1) and a proof-of-concept evaluation (Study 2) to determine whether T4Us enhanced social identity and assessed the intervention implementation.</p> Results <p>In Study 1, five competitive youth ice hockey teams (mean age = 13.0&#xa0;years) completed T4Us at midseason. Overall, athlete leaders <i>(n</i> = 19) and coaches (<i>n</i> = 4) expressed support for the acceptability and feasibility of the initial T4Us workshop in a youth sport setting, including the creation of a unique team “trademark” and the shared leadership mapping exercise. Participants also recommended possible improvements to T4Us (e.g., intervention timing and follow-up booster sessions to reinforce content). In Study 2, a total of 14 competitive youth soccer teams (mean age = 14.7&#xa0;years) completed the revised T4Us at midseason. Descriptive results highlight that athletes’ perceptions of social identity were higher at post-intervention in comparison with pre-intervention. Post-intervention implementation evaluation results revealed that the teams used the game plan to support the team trademark, and athlete leaders and coaches encouraged team members to act according to the team game plan (scores &gt; 5 on a 7-point scale). Interviews with athlete leaders described the different ways in which T4Us enhanced social identity within the team.</p> Conclusion <p>Overall, the initial feasibility evidence and the proof-of-concept evaluation support the further development of T4Us, including a randomized-controlled T4Us protocol.</p>