This thesis considers the different forms of knowledge and ways of knowing generated through the processes and products of practitioner research from an Aristotelian relational perspective. I adopt the term 'gnoseology', which encompasses many different knowledge types, rather than the narrower, yet more commonly used term 'epistemology', and detail the development of a gnoseology framework. I use this framework to examine the understandings generated by a group of international postgraduate learners on a 10-week, intensive English for Academic Purposes course at a private UK institution as they explore the things that puzzle them about their language learning lives. Their explorations are grounded in the principles of Exploratory Practice (EP), a form of practitioner research that proposes learners themselves be viewed as 'key developing practitioners' alongside the teacher. The principles of EP also inform both my research methodology and my approach to classroom pedagogy for the purposes of this study, and the data used is generated naturalistically through the daily activity of the classroom. The thesis offers an account of both the processes and products of the learners' explorations, highlighting some of the potential benefits and tensions that surface as learners engage in exploring their language learning puzzles. It discusses the possibilities of viewing learners as 'key developing practitioners' for the learners themselves, teachers and the academy. Using my gnoseology framework I explore the emergent and developing understandings of the learners that arise through this work as they develop their praxis. I conclude that in contrast to the traditional separation of knowledge types into scientific (episteme), craft (techne) and practical wisdom (phronesis), my data shows these different forms and ways of knowing are multifaceted, interrelated and often operate simultaneously. I suggest that my gnoseology framework is the principle contribution of this thesis as it provides a potentially new way of examining and understanding the nature of, and relationships between, the different forms and ways of knowing produced through practitioner research. I also relate these developing and emerging learner understandings to the principled framework of EP, offering suggestions for its development, with particular regard to issues of relevance, learner expectations, and the processes of puzzling and puzzlement. This critique of EP is also a key contribution of this thesis.