The primary aim of this project is to determine the relative clinical effectiveness of 3 months of chiropractic care and supervised exercise versus supervised exercise in 184 adolescents with sub-acute recurrent, or chronic LBP. Relative effectiveness will be evaluated in the short, intermediate and long term using pain as the primary outcome measure. Secondary aims are to assess group differences in patient self-reported disability, quality of life, perceived improvement, satisfaction, activity levels, lumbar dynamic motion, and trunk muscle endurance. Patients' and caregivers' perceptions of treatment using qualitative interviews will also be assessed.