School principals' ethical considerations and organizational decisions can improve schools' image and social credibility. This study designed and validated Lorestan principals' conceptual, ethical decision-making model. The study has an exploratory mixed-methods design. The qualitative section included grounded theory, paradigm-based theme analysis, and interpretive structural modeling. Exploratory, descriptive methods underpinned the quantitative section. Education experts with scientific experience in decision-making and ethics and one or more articles in those fields constituted the qualitative section's research field. The quantitative section's statistical population comprised Lorestan's nearly 1,000 school principals. Semi-structured interviews with 18 purposively selected school principals provided data for the qualitative section. Random cluster sampling and Krejcie and Morgan's table selected 181 people for the quantitative section. A researcher-made questionnaire was used to collect data in this section. The qualitative data were analyzed using thematic analysis based on the paradigm model and interpretive structural modeling in three stages (open, axial, and selective coding) using MAXQDA 18. Management experts' opinions and Cronbach's alpha coefficient of 0.95 ensured the questionnaire's content validity and reliability. Quantitative data was analyzed using SPSS-25 and SPSS Amos software for confirmatory factor analysis and partial square model. Qualitative findings identified 15 organizing and five overarching themes: contextual factors, causal factors, strategic factors, intervening factors, and outcomes. The quantitative results from structural equation modeling demonstrated that Lorestan school principals' ethical decision-making model fits well.
