Our goal in developing this timeline was to trace the empirical bases of current approaches to L2 pronunciation teaching, with particular attention to the concepts of "accent" and "intelligibility". The process of identifying suitable works for inclusion challenged us in several ways. First, the number of empirical studies of pronunciation instruction is far too small to provide an interesting perspective on the issues. In fact, the dearth of such investigations has been noted many times since at least as far back as the 1960s (Strain 1963; Sisson 1970). Consequently, tracing the roots of contemporary teaching practices required that we expand our purview to consider theoretically-motivated research, as well as influential non-empirical writing about pronunciation. Here we encountered a second problem: the field of applied phonetics and phonology is so diverse that it was very difficult to decide what to omit. The research follows multifarious threads, some of which can directly inform classroom practices, while others are more concerned with general learning influences and processes. In addition, a large body of speculative and opinionated commentary on pronunciation has been published, much of which has never been submitted to empirical test.