Introduction: Community-based participatory research (CBPR) is an effective approach to health promotion, especially in relation to socially disadvantaged groups. However, the long-term implementation of CPBR-based projects on a broad scale is often challenging, and research regarding the sustainable transfer of participatory research is lacking. This limits the scaling-up and public health impact of CBPR. Therefore, this study examines the mechanisms utilized to transfer and sustain the BIG project, a multifaceted CBPR project aimed at promoting physical activity among women in difficult life situations. Materials and Methods: Borrowing from the RE-AIM framework, we analyzed project documentation and conducted a reflection workshop to investigate methods of transferring BIG to new sites as well as strategies from researchers to support project implementation and the maintenance of program activities at those sites. Moreover, we analyzed the reasons for discontinuing program activities at some former BIG sites and the costs involved in transferring BIG. Results: Since its establishment in 2005, BIG was transferred to and implemented at 17 sites. As of the winter of 2019, the program activities were maintained at eight sites. The average duration of sites that continue to offer program activities was more than 9 years. Discontinued sites maintained project activities for an average of 4 years. According to the study findings, the extent of scientific support, the provision of seed funding, and the local project coordinator, the person managing the project at the site, all have a significant impact on the sustainability of the transfer. A patchwork of funding agencies was needed to finance scientific support and seed funding in BIG. The transfer of BIG projects accrued annual costs of approximately EUR20,000 per site; however, long-term project implementation resulted in a decline in the annual transfer costs of BIG. Discussion and Conclusion: The sustainable transfer of CBPR is challenging but possible, and increased support of research and seed funding can facilitate long-term transfer. Nevertheless, other factors in the implementation setting are beyond scientific