Assembling a distinctive genealogy of cybernetic thought situated in relation to Progressive Era technocracy, industrial capitalism, (de)colonial relations, and eugenic machinery, Code uncovers the vital interdependence of informatics, the humanities, and the human sciences in the 20th century. Rather than figuring cybernetics as emerging from Second World War military technologies and post-war digital computing, Code argues that liberal technocrats’ inter-war visions of social welfare delivered via ‘neutral’ communication techniques shaped the informatic interventions of both the Second World War and the Cold War. Tracing how an organizing concept of code linked the work of diverse structurally-minded thinkers, such as Norbert Wiener, Warren Weaver, Margaret Mead, Gregory Bateson, Claude Lévi-Strauss, Roman Jakobson, Jacques Lacan, Roland Barthes, and Luce Irigaray, Bernard Dionysius Geoghegan reconstructs the cybernetic apparatus that spawned new fields, including structural anthropology, family therapy, and literary semiology – and grapples with the unfolding implications of such socio-technical dynamics for 21st-century critical theory, digital media, and data analytics.