This thesis investigates the relationship between organizational size and the decision of using social impact measurements in Swedish socially entrepreneurial organizations, which include organizations and individuals that aim at solving social problems. Data is collected using an online survey, and three different ways to measure organizational size are used and tested whether they have a positive relation-ship with the use of social impact measurement. Organizational size is measured as the yearly turnover, available personnel and the number of members and participants in the organization. The association was analyzed through three different analytical methods, and we also present detailed descriptive statis-tics for the data sample. The results showed significant relationships between available staff as well as members and participants and the use of social impact measurements, while no significant relationship between the yearly turnover and the use of social impact measurements could be confirmed. We suggest a consideration of impact measurements when addressing sustainable organizational development as well as consideration of organizational size for local governments when introducing policies, funding and other support for socially entrepreneurial organizations.