The investigators seek to develop a clinical prediction rule (CPR) to identify patients with a primary complaint of shoulder pain who are likely to benefit from manual therapy to the neck and upper back regions. Manual therapy will include mobilizations (therapist moves the joints in an oscillating fashion) and manipulations (therapist performs a high velocity low amplitude movement) The investigators hypothesize that a cluster of signs and symptoms from the subject history and physical examination will exist that maximize the accuracy of identifying patients with a primary complaint of shoulder pain likely to benefit from this manual therapy treatment based on a reference standard of patient-reported improvement.