Graphical dialogue -the collaborative construction and modification of drawings- forms an integrated part of many human interactions e.g., the construction of sketch maps, architectural designs or explanatory diagrams. Empirical studies have shown significant parallels between the basic mechanisms that underpin verbal and graphical dialogue. These parallels point to the operation of generic mechanisms of interaction that integrate events in different modalities into composite communicative signals. This provides a useful perspective on the design of technologically mediated interactions and suggests there is potential for developing richer forms of human interaction.