Background and Purpose: Chronic neck pain is a common problem. Studies of physical therapy for neck pain often utilize multiple interventions on the same subject making interpretation of the results difficult. The objectives of this study were two fold, 1) to establish the ability to recruit and treat subjects needed for a clinical trial of mobilization vs. massage for neck pain and 2) to estimate the variability of the Neck Disability Index (NDI) in a defined population of patients with neck pain and determine sample size for a trial. Subjects and