The study of allusion has been beset by limiting assumptions, conceptual murkiness, and terminological imprecision; moreover, many poststructuralist theorists regard such study as having been superseded by newer conceptions of intertextuality. This essay seeks to clarify the nature of allusion and the terminology by which it is analyzed and to place it on a firmer footing within poststructuralist literary criticism. I distinguish two forms of allusion often conflated-learned reference and phraseological adaptation–and elucidate the elements of a phraseological adaptation. I distinguish diachronic allusion from synchronic intertextuality, as poststructuralist theorists insist should be done, but then suggest how coordinating the two can enrich the analytic power of each way of conceiving textual interrelation.