The present study was conducted to identify the competencies of high school principals, propose a competency model, and validate the model. The research was carried out in district four of Mashhad in 2015 and examined two questions: 1.What are the dimensions and components of high school principals’ competencies? 2. Is the competency model, derived from this research, valid? In this study, mixed methodology was used and the research design was mixed exploratory since both qualitative and quantitative methods were utilized. In order to collect qualitative data, 19 principals, assistant principals, and senior managers and educational experts of Education Directorate in district four of Mashhad were interviewed. Qualitative content analysis was used and the draft model of high school principals’ competencies was extracted. In the next step, in order to collect quantitative data a self-devised 44-item questionnaire was administered to principals, assistant principals, senior managers and educational experts and 140 questionnaires were collected. For the purpose of data analysis confirmatory factor analysis and AMOS software were used. The results showed that all components of the competency model of high school principals were approved.