Background: In response for the need of a freely available, stand-alone, validated outcome measure for use within musculoskeletal physiotherapy practice, sensitive enough to measure clinical effectiveness, we developed a musculoskeletal patient reported outcome measure. Objectives: This study examined the validity and reliability of the newly developed Brighton musculoskeletal Patient Reported Outcome Measure (BmPROM) within physiotherapy outpatient settings. Methods: Two hundred and twenty four patients attending physiotherapy outpatient departments in South East of England with a musculoskeletal condition participated in this study. The BmPROM was assessed for user friendliness (rated feedback, n=224), reliability (internal consistency and test-retest reliability, n=42), validity (internal and external construct validity, n=224) and responsiveness (internal, n=25). Results: Exploratory factor analysis indicated that a two-factor model provides a good fit to the data. Factors were representative of ‘Functionality’ and ‘Wellbeing’. Correlations observed between the BmPROM and SF-36 domains provided evidence of convergent validity. Reliability results indicated that both subscales were internally consistent with alphas above the acceptable limits for both ‘Functionality’ (α = .85, 95% CI = .81- .88) and ‘Wellbeing’ (α = .80, 95% CI = .75- .84). Test-retest analyses (n= 42) demonstrated a high degree of reliability between ‘Functionality’ (ICC= .84; 95% CI = .72-.91) and ‘Wellbeing’ scores (ICC= .84; 95% CI = .72- .91). Further examination of test-retest reliability through the Bland-Altman analysis demonstrated that the difference between ‘Functionality’ and ‘Wellbeing’ test scores did not vary as a function of absolute test score). Large treatment effect sizes were found for both subscales (Functionality d = 1.10; Wellbeing 1.03). Conclusion: The BmPROM is a reliable and valid outcome measure for use in evaluating physiotherapy treatment of musculoskeletal conditions.