This research is a study of the development of coaching practice and sense of identity of three middle leaders in a primary school who are responsible for leading professional learning. It is of interest because significant responsibility for leading teacher professional learning has been handed to middle leaders since the devolution of management to schools. However little is known about how this leadership of learning is implemented and how leaders might develop for this responsibility. Collaborative inquiry is explored as an approach where middle leaders have space to learn theoretical frameworks, practise coaching skills in an authentic situation and examine the impact. The purpose is to stimulate reflection and guide systematic inquiry into coaching practice for action and change. The ethnographic methodology was deliberately used to allow the research participants to make sense of their world in which they act as coaches. Through linking action and research, ideas about coaching teachers to be skilled critical inquirers were tried as a means of knowledge creation (Cohen, Manion, & Morrison, 2003). The use of participatory action research ensured that the Professional Learning Leaders (PLLs) could work collaboratively to understand the situation supported by myself as a participant researcher. Within five convergent group interviews the PLLs engaged in dialogue and reflection about their practice and the observed impacts of coaching three teachers in a group to be skilled critical inquirers of their classroom practice. Professional literature was used to support their inquiry. The findings confirm that facilitation of reflective dialogue is difficult because it involves challenging the beliefs of others while maintaining an environment of trust. The view that the most effective professional development is collaborative, situated and participatory is also confirmed. Although confirmations are not new information, the learning and involvement in the process through a supported collaborative inquiry approach was a new and transformational experience for the participants where knowledge was created and people changed. The findings reveal that improved coaching practice and identity learning occurred interdependently. Being a coach in the dual position of middle leader and teacher was discovered to cause conflicts. Collaborative inquiry into the causes and impacts of these conflicts helped to clarify the role and responsibility of coaching. The findings suggest that the roles and practice of senior and middle leaders in relation to enhancing teaching and learning in the school must be examined closely. School leaders need to consider how they can structure and support collaborative inquiry for professional learning and building leadership capacity. Drawing on the discoveries and understandings of coaching practice and collaborative inquiry, this research presents a diagram that illustrates the significance of collaboration in the process of improving coaching practice and identity learning.