The purpose of the thesis is to explore excellence in Enquiry-Based Learning (EBL), its philosophical underpinnings, pedagogical implications and possibilities. How pedagogic devices can be used to encourage tutors' reflections on EBL, and is concerned with producing and sharing knowledge in relation facilitating student-centred teaching and learning practices. The study is in the tradition of practitioner research, where my role was that of an educational developer at the Centre for Excellence in Enquiry-based Learning. It is centred around the development of EBL models as pedagogic instruments to facilitate tutors' reflections on their practice. The thesis investigates how to facilitate the incorporation of more student-centred approaches into tutors' practice in a UK university through employing EBL models as a tool for reflection, how these models were introduced to tutors, and the findings from the process. A critical action research approach was undertaken for the educational development practitioner research journey. The primary methods of data collection consisted of interviews with students and tutors, and data obtained during individual reflections and group discussions in a series of workshops that involved tutors studying EBL models. Thirty-one tutors were involved in these workshops and interviews where they quantitatively and qualitatively explored multiple dimensions of teaching and learning. Content analysis of the results was conducted on the data with an emphasis on dilemma analysis to gain insights into tutors' decisions about their practice, and an empirical abductive strategy was employed to inform the development of new EBL models. In the course of the action research phases two new EBL models were iteratively developed informed by the literature and stakeholders. Finally, a new Student Involvement in Learning and Teaching Model was proposed, empirically abducted from student narratives derived from photo-elicited interviews. This Model constituted the development of a new conceptual framework for thinking about EBL within the context of broader teaching and learning practice. This study articulates new student involvement dimensions which conveyed the nature of power within the proximal processes of teaching and learning. The thesis contributes towards the practice of educational development by documenting both the process and outcomes of introducing EBL and learning and teaching models to tutors as reflective instruments, and by proposing a new perspective on excellence in EBL where student involvement is enhanced when reciprocal power relationships exist in the proximal processes between tutors and students. Tutor decisions were framed as a series of dilemmas created by external contextual influences (the University social micro, meso, exo and macro-systems); and internal factors (the tutors' personal force-resource characteristics) which affected tutors' reported actual and espoused ideal practice. The data demonstrated that most tutors espoused including more EBL, but they preferred an incremental change in their practice.