QUESTION: Is the Assessment of Physiotherapy Practice (APP) a valid instrument for the assessment of entry-level competence in physiotherapy students? DESIGN: Cross-sectional study with Rasch analysis of initial (n=326) and validation samples (n=318). Students were assessed on completion of 4, 5, or 6-week clinical placements across one university semester. PARTICIPANTS: 298 clinical educators and 456 physiotherapy students at nine universities in Australia and New Zealand provided 644 completed APP instruments. RESULTS: APP data in both samples showed overall fit to a Rasch model of expected item functioning for interval scale measurement. Item 6 (Written communication) exhibited misfit in both samples, but was retained as an important element of competence. The hierarchy of item difficulty was the same in both samples with items related to professional behaviour and communication the easiest to achieve and items related to clinical reasoning the most difficult. Item difficulty was well targeted to person ability. No Differential Item Functioning was identified, indicating that the scale performed in a comparable way regardless of the student's age, gender or amount of prior clinical experience, and the educator's age, gender, or experience as an educator, or the type of facility, university, or clinical area. The instrument demonstrated unidimensionality confirming the appropriateness of summing the scale scores on each item to provide an overall score of clinical competence and was able to discriminate four levels of professional competence (Person Separation Index=0.96). Person ability and raw APP scores had a linear relationship (r(2)=0.99). CONCLUSION: Rasch analysis supports the interpretation that a student's APP score is an indication of their underlying level of professional competence in workplace practice.