BackgroundMoral distress is common phenomenon that has negative consequences on nurses, patients, and healthcare systems. This study aims to design and evaluate an educational program to reduce moral distress in nurses.MethodsThis multiphase mixed-method study was done in three stage on February 2021 in Shiraz/Iran. In pre-implementation stage, a content analysis study was conducted on 12 participants were interviewed using purposive sampling and then the program was designed according to qualitative data, panel of expertise and literature review according the seven steps of Ewles and Sminett’s model and implemented in one group on 40 nurses using a quasi-experimental design. In Post-Implementation stage, effectiveness of program was evaluated through quantitative and qualitative methods. Quantitative data were gathered by Hamric's 21-question moral distress questionnaire analyzed via SPSS v.25 and analysis of variance repeated measures test. Also, a content analysis study was conducted on 6 PRMD participants using purposive sampling. In Program evaluation stage, convergence of quantitative and qualitative data and the effects of the program were examined. Trustworthiness of qualitative data was accomplished by Lincoln and Guba criteria.ResultsFirst quantitative study revealed the causes of moral distress consisted of deficiency in professional competency, unsuitable organizational culture, personal factors, environmental and organizational factors, management factors, insufficiencies in proficient and efficient communication and nurses' observation of moral dilemma. Results of quantitative stage showed that there was a significant difference (p< 0.05) between the mean score of moral distress before, after, 1 and 2 months after the intervention. The participants in secondary qualitative stage, reported increasing their moral knowledge and skills, improving ethical climate, and moral empowerment.ConclusionThe use of different educational tools and teaching methods and the participation of managers in designing strategies had a very effective role in the effectiveness of this educational program.