Traditional accounts of language processing suggest that monologue--presenting and listening to speeches--should be more straightforward than dialogue--holding a conversation. This is clearly not the case. We argue that conversation is easy because of an interactive processing mechanism that leads to the alignment of linguistic representations between partners. Interactive alignment occurs via automatic alignment channels that are functionally similar to the automatic links between perception and behaviour (the so-called perception-behaviour expressway) proposed in recent accounts of social interaction. We conclude that humans are "designed" for dialogue rather than monologue.