Abstract
The value of coaching teachers by professional coaches in their school context is recognized to provide them with sustainable professional development (SPD). However, little is known about the coaching process promoting SPD and the variables that can explain its quality. Three objectives were pursued: 1) to describe the quality of the coaching process; 2) to determine the characteristics of the coach, and 3) to identify the characteristics of the school context that can explain quality to promote SPD. An Embedded Multiple-Case Study Design was conducted at two different schools. Results describe that the quality of the coaching process was clear in its orientation to precise goals, its complexity, and its dynamism. The coaches’ characteristics that can explain the quality of the coaching process to promote SPD are their perceptions of the context and their conceptions. The most important characteristic of the context that can reveal the quality of coaching enacted is the leadership of the school principal and the teachers’ culture of collaboration.