Background There is no instrument currently available to assess the essential nursing competency of clinical reasoning (CR). Purpose The purpose of this study was to develop and test the psychometric properties of CR assessment instrument appropriate for use with nursing students across different types of programs. Methods H. M. Huang et al.'s (2018) Framework of Competencies of Clinical Reasoning for Nursing Students was used to guide this study. Two rounds of Delphi study and confirmatory factor analysis (CFA) were conducted to test content and construct validity. Internal consistency was tested for reliability. Results The four-domain, 16-item Likert-scale Clinical Reasoning Scale (CRS) was developed. One thousand five hundred four nursing students currently enrolled in three different types of nursing programs completed the CRS. The content validity index was.85-1.0, the CFA indicated goodness of fit, and the Cronbach's α score range was.78-.89. Conclusion The CRS is a valid and reliable tool for assessing CR in nursing students in different types of nursing program.