A substantial body of empirical evidence indicates that interactional context has a key influence on the form and interpretation of language. This paper provides an overview of a series of experiments which indicate that interactional context also plays a key role in the interpretation of drawings and sketches. Two experimental graphical communication tasks, analogous to definite reference tasks, are described. The findings from these tasks show significant parallels between the mechanisms of co-ordination in graphical dialogue and natural language dialogue. Specifically; participants match on drawing types above chance, 'graphical referring expressions’ reduce with repetition in an interaction, direct interaction promotes the use of more abstract drawings, and community-specific graphical conventions emerge in experimental ’sub-communities'.