In this article I argue for the establishment of "Applied Linguistic Historiography" (ALH), that is, a new domain of enquiry within applied linguistics involving a rigorous, scholarly, and self-reflexive approach to historical research. Considering issues of rationale, scope, and methods in turn, I provide reasons why ALH is needed and argue that, while it can borrow from "Linguistic" Historiography, it should also distinguish itself, for example, by paying more attention to histories of "practice" as well as ideas, with corresponding methodological emphases and challenges. Making specific reference to the histories of applied linguistics and of language learning and teaching, I identify ways in which theories, theory-practice links, and practices themselves can be investigated historically in a more rigorous and ultimately useful manner. Overall, I show that innovation to establish this new domain of enquiry in applied linguistics involves reflection on research methods but also on more fundamental concerns.