Background: In Australia, performance of nursing students during clinical placements is assessed against national practice standards. Access to a tool that has a common assessment language can reduce confusion across assessors, practice areas and programmes of nursing. Aim: To revise the existing Australian Nursing Standards Assessment Tool (ANSAT) to reflect the 2016 Nursing and Midwifery Board of Australia (NMBA) registered nurse standards for practice and investigate validity of the revised tool. Design: Non-experimental study involving tool development and psychometric testing. Participants/setting: Registered nurses experienced in assessment of students from academic and clinical settings participated in the first phase of study; ANSAT scores of students across three universities were used for the second phase. Methods: A two-phased study was conducted. Phase one involved tool revision and content validation using a modified Delphi approach. Phase two involved validation of the revised tool used to assess student performance on clinical placement. Results: A 23-item tool was developed in phase one from input of eight experts, with the content validity ≥.83. The phase two field test analysed 7696 completed tools. Exploratory factor analysis extracted one factor labelled professional practice performance. The revised ANSAT demonstrated high internal consistency (Cronbach’s alpha = .985). Comparison of mean total ANSAT scores determined the tool is sensitive to differing levels of performance across year levels, placement length, and sites with statistical significance observed at p < .001. Conclusions: The revised ANSAT is a valid tool with high internal consistency that can be used to measure performance against NMBA registered nurse standards for practice.