Many types of everyday and specialized reasoning depend on diagrams: we use maps to fnd our way, we draw graphs and sketches to communicate concepts and prove geometrical theorems, and we manipulate diagrams to explore new creative solutions to problems. While the linear and symbolic character of verbal language has long served as the predominant model of human thought, it is remarkable how — through a range of contexts — thinking and communication critically depend on manipulations of external, ofen non-linear, (...) and manipulable iconic-diagrammatic vehicles. In this issue of Pragmatics and Cognition we explore such diagrammatic reasoning, that is, of individual and intersubjectively distributed cognitive processes relying on external representations (i.e. diagrams in a broad sense) as tools for thinking and communicating. (shrink)