This thesis explores the transmission of craft knowledge in midwifery, examining the mediation of practice learning within mentor/student pairs. It is an in-depth exploration of non-formal learning as perceived by a sample of student midwives at various stages of their preparation programmes across England. The theoretical underpinning stems from literature on non-formal learning, incorporating Eraut's analysis of non-formal learning and Polanyi's philosophy of tacit knowledge. A sample of fourteen student midwives recorded their experiences of learning and support in clinical practice for ten days in audio-diary format. The diaries were analysed within a narrative analysis framework to capture the 'voice' of the learners, who described the challenges inherent in learning and acquiring the craft of midwifery. Discourse analysis was used to interrogate the data. This method enabled discovery of pattern and order in everyday language-in-use. Unique information emerged within students' individual interpretive repertoires. The lengthy audio-diaries illuminated contexts and linguistic expressions which conveyed the socio-cultural positioning of the student midwives. The method was found to be compatible with non-formal learning and the epistemological perspective selected because of the organic nature of craft knowledge. Student midwives' reflexive accounts identified a range of 'tools' used by mentors, which influenced acquisition of practical competence and cognition. These tools included not only physical teaching aids, but also signs, modelling and other means of semiotic mediation. This thesis reveals the power of formative learning and situated support in midwifery practice. An argument is developed for mobilising hidden, tacit knowledge which often exists on the borders of the formal curriculum.