There are currently no effective methods for treating and preventing chronic pain. The aim of this thesis was to study prognostic factors for health care utilization, and the long-term outcomes of tailored behavioral medicine treatment for patients with musculoskeletal pain. Another aim was to increase knowledge about physical therapists’ assessment and analysis of patients’ pain conditions and to investigate the potential of subgrouping patients based on prognostic factors. Methods: In Study I, a prospective population-based cohort was followed over 21 years. Data from three measure points were analyzed: 1995 (n=2425), 2007 (n=1582) and 2016 (n=1184). Study II was a 10-year follow-up of randomized controlled trial (n=97), comparing tailored behavioral medicine treatment and exercise-based physical therapy. In Study III, a descriptive and explorative design was applied, using data from video-recordings of 12 physical therapists. In study IV, assignment to three subgroups based on the Örebro Musculoskeletal Pain Screening Questionnaire was validated against reference instruments, and the stability between two points of measurement was investigated in patients (n=40) who were seeking primary health care due to musculoskeletal pain. Results: Chronic pain, female gender and high age predict high health care utilization over 21 years, and a trajectory of stable high health care utilization over the entire period. The differences between groups in favor for tailored behavioral medicine treatment reported at post-treatment and after two years, were not maintained at the 10-year follow-up. A majority of the physical therapists assessed factors for poor prognosis. The analyses were mainly based on biomedical assessments and none of the physical therapists included behavioral factors. Subgroup assignment according to the Örebro Musculoskeletal Pain Screening Questionnaire appears to be valid and stable over time. Conclusion: Prognostic factors such as chronic pain and female gender need to be considered when allocating health care resources and planning treatment to improve long-term outcomes. The treatment should also be tailored based on individual functional behavioral analyses of key behaviors and on patient´s biomedical and psychosocial condition, including strategies for maintenance of behavioral changes. Evidence-based methods for integrating behavioral medicine treatment into physical therapy need to be further evaluated and improved.