BACKGROUND AND PURPOSE: Physiotherapists develop clinical reasoning theories and applied manual therapy skills through a variety of educational exposures. No studies have assessed the importance of selected theories such as the convex-concave rule, capsular pattern and scapulohumeral rhythm during clinical decision-making by physiotherapists. The present study investigated which variables physiotherapists considered were associated with the importance of these theories during practice and investigated physiotherapists' perception of translational motion biomechanics of the glenohumeral (GH) joint. METHOD: Six hundred and sixty physiotherapists in the USA volunteered to participate in this study. Using ologit regression analyses, the identifier themes and clinical background characteristics were associated with importance of peripheral biomechanics in manual therapy application and reliability/validity of the scapulohumeral rhythm theory in predicting pathological sequences of the shoulder complex. An intraclass correlation coefficient (ICC) was used to determine agreement regarding necessary translation of the GH joint for normal movement. RESULTS: The majority of physiotherapists indicated that all theories were important or very important during treatment decision-making and reported frequent utilization. Regression models identified that the importance placed on peripheral biomechanics was negatively influenced by academic qualification (bachelors and masters degrees) and gender (men were less likely to report that scapulohumeral rhythm was a reliable/valid predictor of shoulder pathology). ICC values identified excellent agreement among clinicians regarding translational motion. CONCLUSIONS: The importance of biomechanics of the periphery for use, validation and frequency was based heavily on adoption of selected theories of glenohumeral movements despite evidence that suggests the theories lack validity.