Modernism: Keywords presents a series of short entries explaining the diverse and often contradictory meanings of words used with frequency and urgency in “written modernism.” Spanning the “long” modernist period (from about 1880 to 1950), this work aims not to define the era’s dominant “beliefs,” but to highlight and expose its salient controversies and changing cultural thought. Guided by the cultural lexicography developed by Raymond Williams in his groundbreaking work, Keywords (1976), the entries here focus on words with unstable meanings and conflicting definitions, tracking disparities to capture pivotal matters of discussion and debate. By selecting keywords that the modernists were utilizing themselves, and by drawing from a broad and eclectic range of writings, Modernism: Keywords illuminates a path to restoring the language of the modernist period to its life in the public sphere of its time.