Collaboration between services has often been suggested as a means to increase effectiveness and reduce costs especially in the care and rehabilitation of long-term illness. In Sweden, a special legislation named SOCSAM was introduced in 1994, enabling financial collaboration between governmental and municipal authorities. In this paper we report on a qualitative study on collaboration around patients with musculoskeletal diseases. The aim of the study was to assess differences in goal formulation, collaboration and communication between staff in intervention health centres that have implemented co-financing projects and health centres working under conventional conditions. Focus group interviews were performed with staff at intervention and control health care centres. We found that the interdisciplinary collaboration had improved in the intervention health care centres compared to the controls. Our findings suggest that co-financing can enhance development of better forms of interdisciplinary and interorganisational collaboration through legitimising formulation of common long-term goals, while emphasising mutual benefits.