We believe there is a need to identify a practical method for determining objective measurement of forward head posture. In our study, we determined the within-tester and between-tester reliabilities for clinical measurements of static, sitting, forward head posture using the cervical range of motion (CROM) instrument. Repeated measurements were made using a standardized protocol on 40 patients seated in a standardized position. The seven testers had from 1 to 8 years of clinical experience. All measurements were recorded by the same investigator. The intraclass correlation coefficient (ICC[1,1]) was used to quantitate within-tester and between-tester reliability. Measurements of forward head position performed by the same physical therapist had high reliability (ICC = 0.93). Good reliability (ICC = 0.83) was demonstrated when different physical therapists measured the forward head posture of the same patient. We concluded that measurements of forward head posture made by physical therapists trained in the correct use of the CROM instrument are reliable. This reliability is important for determining the effectiveness of treatment programs. On the basis of our data, the CROM instrument will assist clinicians in the objective evaluation and reassessment of the patient population demonstrating forward head posture.