Objectives: To identify relative provider costs, clinical outcomes, and patient satisfaction for the treatment of low back pain (LBP). Methods: This was a practice-based, nonrandomized, comparative study of patients self-referring to 60 doctors of chiropractic and 111 medical doctors in 51 chiropractic and 14 general practice community clinics over a 2-year period. Patients were included if they were at least 18 years old, ambulatory, and had low back pain of mechanical origin (n = 2780). Outcomes were (standardized) office costs, office costs plus referral costs for office-based care and advanced imaging, pain, functional disability, patient satisfaction, physical health, and mental health evaluated at 3 and 12 months after the start of care. Multiple regression analysis was used to correct for baseline differences between provider types. Results: Chiropractic office costs were higher for both acute and chronic patients (P < .01). When referrals were included, there were no significant differences in either group between provider types (P > .20). Acute and chronic chiropractic patients experienced better outcomes in pain, functional disability, and patient satisfaction (P < .01); clinically important differences in pain and disability improvement were found for chronic patients only. Conclusions: Chiropractic care appeared relatively cost-effective for the treatment of chronic LBP. Chiropractic and medical care performed comparably for acute patients. Practice-based clinical outcomes were consistent with systematic reviews of spinal manipulation efficacy: manipulation-based therapy is at least as good as and, in some cases, better than other therapeusis. This evidence can guide physicians, payers, and policy makers in evaluating chiropractic as a treatment option for low back pain.