School principals were invited to perform a reflective analysis of their teacher's supervision practices, with the goal of consolidating the knowledge derived from experience, developing appropriate methods, and adapting their interventions. Data were collected from 12 semi-structured interviews. The interview to the double method was used to facilitate the representation and formalization of professional experience to enable these school leaders to articulate their supervisory practices, and adapt and integrate new attitudes or behaviors towards these practices. Interviews were recorded and later analyzed by using mixed coding. The instructions were organized around knowledge, personal skills (climate, work relations, and attitudes), and know-how (prioritization of the supervision, data collection, feedback, and task-sharing). The discussion focuses on leading for teacher's initial and continued training with emphasis on the practitioners' role. "Components of Professional Practice" is appended to this document. (Contains 1 figure.)