Background Licensed nurses working in long-term care facilities experience ethical challenges if not resolved can lead to moral distress. There is a lack of an English-language validated tool to adequately measure moral distress in the long-term care setting. Aims To describe the modification and psychometric evaluation of the Moral Distress Questionnaire. Methods Instrument development and psychometric evaluation. Internal consistency using Cronbach’s α to establish reliability was conducted using SPSS version 27.0 while SPSS Amos version 27.0 was used to perform a (...) confirmatory factor analysis of the Moral Distress Questionnaire Participants A national sample of US-licensed nurses who provided direct resident care in long-term care settings were recruited via a targeted sampling method using Facebook from 7 December 2020 to 7 March 2021. Ethical Consideration The study was approved by the university’s human research protection program. Informed consent was provided to all participants. Results A total of 215 participants completed the surveys. Confirmatory analysis indicated that the 21-item scale with a 4-factor structure for the Moral Distress Questionnaire model met the established criteria and demonstrates an acceptable model fit (CMIN/DF = 2.0, CFI = 0.82, TLI = 0.77, RMSEA = 0.07). Factor loadings for each item depict a moderate to a strong relationship (range 0.36–0.70) with the given underlying construct. Cronbach’s α coefficient was 0.87 for the overall scale and 0.60–0.74 for its subscales which demonstrate good reliabilities. Discussion This is the first English-language validated tool to adequately measure moral distress in the long-term care setting experienced by US long-term care nurses. This reliable and well-validated tool will help identify moral distress situations experienced by US long-term care nurses. Conclusion The modified 21-item English version of the Moral Distress Questionnaire is reliable tool that demonstrates good psychometric properties to validly measure sources of moral distress among direct resident care nurses. (shrink)