The Australian Midwifery Standards Assessment Tool (AMSAT) was developed against the Competency Standards for the Midwife in 2017 to enable consistent assessment of midwifery student performance in practice-based settings. The AMSAT requires revision and re-validation as the competency standards have now been superseded by the Midwife Standards for Practice 2018.This research revised and validated the AMSAT to assess performance of midwifery students against the Midwife Standards for Practice 2018 and assessed its sensitivity.A mixed-methods approach was used in a two-phase process. Phase one involved the re-wording of the AMSAT and behavioural cue statements in an iterative participatory process with midwifery academics, assessors and students. The tool was field-tested in different assessment environments in phase two. Completed assessment forms were statistically analyzed, whilst assessor surveys were analysed using descriptive statistics and qualitative content analysis.Analysis of AMSAT (n=255) indicates the tool as: internally reliable (Cronbach alpha>.9); valid (eigenvalue of 16.6 explaining 67% of variance); and sensitive (score analysis indicating increased levels of proficiency with progressive student experience). Analysis of surveys (n=108) found acceptance of the tool for the purpose of summative and formative assessment, and in the provision of feedback to midwifery students on their performance.This study demonstrates that the re-developed AMSAT is a valid, reliable and acceptable tool to assess midwifery students' performance against the Australian Midwife Standards for Practice This user-friendly tool can be used to standardize midwifery student assessment in Australia and enable continued benchmarking across education programs.