Self‐assessment is a fundamental skill for professionals because self‐assessment can promote self‐regulated learning and professional development. However, studies reporting the use of self‐assessment instruments in the professional training context are scarce. This study aimed to re‐evaluate the psychometric properties of the Self‐assessment Practice Scale (SaPS), which was originally developed in the school context, and extend its use to the professional training context. A sample of 200 investigative interviewer trainees from Australia and North America were invited to complete the modified SaPS. After removing misfitting items, the confirmatory factor analysis results confirmed a first‐order four‐factor solution. The multidimensional Rasch analysis demonstrated that the resultant 16 items had satisfactory fit to the Rasch model. In general, the results supported the use of the 16‐item modified SaPS as a valid measure for the sample in this study. The potential of using the SaPS in professional training contexts is discussed. Copyright © 2020 Brian Towers (BRITOW) and John Wiley & Sons Ltd.