This article examines textbooks, especially history textbooks, seeking to contribute to an emerging body of scholarship that endeavors to understand the nature, specific properties, and characteristics of this medium. Using systemic functional linguistics and a context-based perspective of language as its theoretical point of departure, it argues for a dual imagining of the textbook as discourse and genre. In imagining the textbook, the article calls for a rethinking of comparative textbook research in the future, based on a novel cluster of conceptual priorities deriving from postmodern thought.