Objective: The purpose of this study was to investigate changes in pain, disability, and range of movement after cervicothoracic manipulation plus exercise therapy in individuals with unilateral shoulder impingement syndrome. Methods: Forty-one patients (30 men, 11 women; aged 47 ± 9) diagnosed with unilateral shoulder impingement syndrome attended 10 sessions for 5 weeks (2 sessions/wk). Eligible patients were randomly allocated to 2 study groups: cervicothoracic manipulation plus exercise therapy (n = 21) or home exercise program (n = 20). The outcomes measures included the visual analog scale (VAS); the Disabilities of the Arm, Shoulder, and Hand score; Shoulder Disability Questionnaire; subacromial impingement syndrome (Hawkins-Kennedy Test and Neer Test); and shoulder active range of motion (movements of flexion, extension, rotation, adduction, and abduction). Assessments were applied at baseline and 24 hours after completing 5 weeks of related interventions. Results: After 5 weeks of treatment significant between-group differences were observed in the Disabilities of the Arm, Shoulder, and Hand score (P = .012); however, no statistically significant differences were achieved for Shoulder Disability Questionnaire (P = .061) and pain intensity (P = .859). Both groups improved with regard to disability and clinical tests for detecting subacromial impingement syndrome. Conclusions: This clinical trial suggests that cervicothoracic manipulative treatment with mobilization plus exercise therapy may improve intensity of pain and range of motion compared with the home exercise group alone; the home exercise group had significant changes for flexion, extension, adduction, and abduction, but not for external and internal rotation movement in patients with shoulder impingement. (J Chiropr Med 2017;16:85-93)