While it is not likely that all patients who have with shoulder pain will benefit from manipulation (thrust and non-thrust) of the cervicothoracic spine, it is possible that a subgroup exists that will experience rapid and dramatic improvement with the use of these manual physical therapy techniques. It is our specific aim to develop a clinical prediction rule (CPR) to identify patients with a primary complaint of shoulder pain who are likely to benefit from cervicothoracic manipulation. The purpose of a CPR is to improve the clinician's accuracy in predicting a diagnosis or an expected outcome. For example, CPRs exist to improve the accuracy of diagnosing ankle fractures in individuals with acute injuries,predict the likelihood of death within four years for individuals with coronary disease, or determine when cervical radiographs are required for patients who have experienced neck trauma. The process of developing and testing a CPR has been described in detail elsewhere. Although CPRs can be developed to improve the accuracy of making a certain diagnosis, the focus of this project is to develop a CPR to predict a certain treatment outcome. The development of a CPR utilizes diagnostic properties of sensitivity, specificity, and positive and negative likelihood ratios, which are based on the individual patient. Thus their interpretation can be readily applied to an individual patient. Development of a CPR to accurately predict which patients with shoulder pain will likely experience a clinically meaningful improvement in pain and function with cervicothoracic spine manipulation before treatment would be immensely helpful for clinicians in the decision-making process. Thus the purpose of this project is to develop a CPR to identify patients with shoulder pain likely to benefit from cervicothoracic spine thrust and non-thrust manipulation.