“Of all affairs” said the educationalist and philosopher John Dewey, “communication is the most wonderful” (Dewey, 1925, p. 135). There are several reasons why modern psychology would (and should) agree with this century old pronouncement. Communication – and its close conceptual relative, dialogue – creates and transforms not only the individuals involved in it, but the realm of meanings that could be involved in it. It is not only the key process within which psychological phenomena become manifest but also the key process through which the psychological sciences themselves derive their meanings and validate themselves. Communication is dramatically central in the lives of human adults in diverse spheres of life, of non human primates, of neurons in engagement with each other in an embodied world, of computer programmes and machines designed to ‘communicate’ and ‘respond’ in the contexts they are embedded in, and above all, in the lives of very young infants. And it has been studied extensively in all of these fields.