Purpose: In response to the growing need for educational leaders who possess ethical, critical and reflective qualities, a training program was developed based on ethics as a reflective critical capacity and on Starratt's three-dimensional model. This paper aims to describe the impact of the program on ethical decision making and on educational leaders' ethical competencies. Design/methodology/approach: A three-year action-research study was conducted with three groups of educational administrators, totalling 30 participants. Mixed methods were used for data collection: a pre- and post-training questionnaire, individual semi-structured interviews and group interviews. The questionnaire data were analyzed using SPSS software and interview data were analyzed using thematic analysis. Findings: Results from the pre-test indicate that, prior to the training program, participants rarely possessed all three ethical dimensions. Post-test results show how participants experience a significant readjustment process characterized by three different stages which have been called the transformative cycle. Qualitative results show the impact of the training program on improved ethical awareness, judgement structuring, a sense of responsibility, and overall professional conduct. No significant difference is observed between male and female participants but statistically significant differences are found according to number of years of experience and to work situation. Practical implications: Developing sound ethical expertise appears to be promising in training future educational administrators and in improving their leadership skills. Originality/value: This study is original in many aspects. Theoretically, it is based on a self-regulated rather than hetero-regulated approach to ethics and calls for descriptive rather then normative foundations to ethical leadership. With regard to its methodology, it used mixed methods adapted to action research as well as original data collection instruments. (Contains 5 figures, 1 table and 4 notes.)