One broad goal for English for Academic Purposes students is to learn to write effectively so they can succeed in their chosen academic studies. The teaching of academic writing sensitive to context and texts has benefited from disciplinary based writing studies, allowing EAP teachers and their students to become better informed about the valued writing practices of various disciplines. A further development in this area can be gained by investigating from a linguistic perspective the role of writing for learning in those disciplines. This paper reports on a longitudinal study which mapped from a lexicogrammatical perspective how L[subscript 1] education students' writing developed as their disciplinary knowledge increased. Systemic functional linguistics provided the theoretical framework for the study and the analytical tools. Reasoning and explaining, reporting and engaging with knowledge claims, and engaging with the discipline as a future practitioner were intrinsic to the learner discourse of education in this study. The contextualised descriptions of the lexicogrammatical choices the students made in their writing provide authentic disciplinary examples for EAP writing teachers. These resources will allow EAP teachers and their students to examine writing not only from the perspective of learning to write, but from the perspective of writing to learn in the discipline. (Contains 1 figure and 6 tables.)