Since the late 1980s, concepts of `discourse' have ascended and diversified in educational research that undertakes critical analyses of inequitable forms of power. This prominence and diversity is evidenced in a recent special issue of _Discourse: studies in the cultural politics of education_, 18(3), on the theme of "Critical Discourse Analysis in Educational Settings". My paper outlines key trends in the conception of `discourse', as theorized and as put into analytic use. I point up some tense contradictions in and across these trends, often within a single research project. I argue that tensions hinge significantly around how far one is willing to push a Foucauldian _post_-humanist (or post-foundational) logic for stressing `discursive' (as against human/social) grounds of agency behind formations of power/knowledge in institutional domains. While the post-humanist push has yielded sophisticated breakthroughs beyond earlier `ideology critiques', I argue, it has also led critical research down serious primrose paths. These include an epistemic idealism (despite prominent refutations of this charge), and a loss of capacity to theorize fairly systemic and durable forms of power, "even the `unity in difference' of a complex structure" (Hall, 1985: 92). I conclude with suggestions for ameliorating these problems by recuperating the sophistications of discourse analysis within _neo_-humanist projects of critical educational research.