Low back pain is a leading cause of disability in the United States. Many patients have myofascial pain and/or articular dysfunctions and undergo a variety of therapies without knowing what works the best. Practitioners' diagnoses vary depending results of their manual palpation. Subsequently, ambiguity and controversy arise. The major goal of this study is to compare the treatment outcome and cost- effectiveness of allopathic, chiropractic, and combination of both in the treatment of mechanical low back pain due to myofascial and articular dysfunctions. The study has four specific aims: 1) to determine which therapy is the most cost-effective for treating low back pain; 2) to examine the inter-examiner reliability of manual diagnostic procedures and the effect of interprofessional training; 3) to determine the prevalence of the myofascial and articular dysfunctions; 4) to observe the clinician- patient encounter patterns and their relationships to the outcomes. The study has two stages. In stage I, inter-examiner reliability will be studied using 78 subjects separated into two groups (one with myofascial pain and the other with articular dysfunction). Four allopathic and four chiropractic physicians will participate and half of them will receive training before the study. In stage II, we will screen approximately 1000 patients and select 300 patients for a randomized controlled trial involving four treatment group: back school (as control), back school and myofascial therapy, back school and chiropractic manipulation, and combined therapies. Treatment will last three weeks. The outcome variables will be evaluated four times, i.e. Week 0,3, and again at one week and six months after completion of therapy. Pain and disability questionnaires, clinical outcomes and cost data will be collected and analyzed using appropriate statistics. Clinician-patient encounters will also be observed throughout the second stage. This study has several strengths: involvement of one major allopathic university and one major chiropractic college, addressing the cost- effectiveness issue of low back pain therapy with multiple therapies, use of multiple outcome measures, and true multi-disciplinary collaborations. The result of this project not only will improve the practitioners' skills, but also will have important implications to national practice guidelines.