This paper analyzed social entrepreneurship and nonprofit organizations, with a particular focus on veterans' associations as a specific model. In the theoretical part, the basic concepts of social entrepreneurship were examined, including its development, key principles, and the legal and institutional framework that regulates this field in Croatia. One of the topics covered was the difference between the social economy and social entrepreneurship, highlighting their similarities and differences in goals and methodology. The paper also addressed the legislative framework and legal forms available for establishing nonprofit organizations engaged in social entrepreneurship, such as associations and cooperatives. Institutional support and legal regulations were recognized as key factors for the success and sustainability of these organizations. In the empirical part, the association Ronilački klub veterana 4. gardijske brigade was presented. The paper showed how such associations could function as catalysts for social change. The club engages in psychosocial rehabilitation of veterans through innovative activities, such as therapeutic diving and ecological initiatives. Their focus is on activities that reduce stress levels and help treat post-traumatic stress disorder (PTSD). Through the project "Ja sam PAUK," this association provides support to veterans while simultaneously contributing to environmental conservation and community strengthening. Special emphasis was placed on the SROI analysis of the project, which demonstrated the high social value of the initiative. An SROI ratio of 4.36:1, adjusted according to sensitivity analysis, confirms that the project has a significant positive impact on society, highlighting its sustainability and potential for expansion. In conclusion, the paper provides a theoretical framework and empirical evidence that emphasize the importance of social entrepreneurship in driving social change. It is necessary to improve the legislative framework to support the development and long-term sustainability of social enterprises. Additionally, it is recommended to intensify research focused on measuring social change and strengthening institutional support for these enterprises.