In Sweden, a trial legislation called SOCSAM was introduced in 1994 to improve collaboration and decrease costs for society through allowing co- financing and joint political steering across welfare services. The aim of this thesis was to assess if co-financed collaboration between primary health care, the social insurance offices and social services contributed to improved care and rehabilitation for people with musculoskeletal disorders. This research project assessed the effects of a natural experiment. Patients attending health centres with co-financed collaboration were compared to patients attending control health centres. One hundred thirty eight patients were followed prospectively for one year. Information about health status, health care contacts and sick leave were collected. The results showed no significant differences between patients in the DELTA centres and the controls concerning change in health status between baseline and 12 months follow-up were found. At 12 months follow up, 31% in the DELTA group and 32% in the control group were on sick leave.