Background: The assessment of shoulder mobility is an integral component of the physical therapy examination. Recognizing a mobility loss may assist the physical therapist in making a differential diagnosis, measuring improvement or deterioration, determining functional impairment, and planning interventions. Reliable measurement instruments and procedures are therefore essential to both the clinician and researcher desiring to objectively monitor disease progression, outcomes, and mobility impairments. Objectives: The purpose of this review is to summarize the literature on the reliability and concurrent validity of clinical measurements used to quantify osteokinematic mobility of the shoulder. Major findings: The reliability of shoulder mobility measurements is highly variable with no consistent advantage of instrumentation or procedures. Inclinometric measurement reliability coefficients ranged from 0.11 to 0.99, with goniometry -0.22 to 0.99 and visual inspection 0.18 to 0.98. Reliability was independent of symptom state and measurement approach (passive versus active), although there was a trend for intrarater reproducibility exceeding interrater. Extension, horizontal abduction, and adduction measurements were limited to one investigation which utilized passive goniometric measurements. Research investigating the concurrent validity of instruments and procedures was limited, although favorable when comparing small versus large goniometers and goniometry to a digital level. Conclusions: A consensus for choosing instruments and/or procedures was not conclusive based on comparable reliability reports and ranges. Instruments used to quantify shoulder mobility cannot be used interchangeably with confidence given the paucity of concurrent validity reports. Clinicians should recognize both the merits and limitations of the instruments and procedures that they incorporate into practice.