The number of Sport-for-Development (SFD) organizations is growing worldwide, aiming to foster social change through sport. At the same time, pressure is increasing to professionalize and maintain their relevance. Although social innovation is considered essential, it remains unclear how it takes shape within SFD and when it effectively creates social value. This dissertation explores these issues through four studies. The findings show that SFD innovation mainly focuses on product and process improvements, while transformative innovation remains underexplored. Failed implementations highlight the importance of alignment with values, context, and capacities. In addition, resources such as human capital, trust, and care play a key role. Ultimately, successful social innovation depends on meaningful alignment with stakeholders, recognition of relational processes, and a shared system-level vision, which together enable sustainable social change.