Two features that set DRT apart from other varieties of dynamic semantics is that it is representational and non-compositional. In the 1980s, the founding years of dynamic semantics, these features made DRT a controversial theory, though by now those controversies have abated. DRT’s main innovation, beyond the Montagovian paradigm which was then considered orthodox, is that it introduced a level of mental representations, called “discourse representation structures” (DRSs). The basic idea is rather straightforward. It is that a hearer builds up a mental representation of the discourse as it unfolds, and that every incoming sentence prompts additions to that representation. This picture has always been commonplace in the psychology of language. DRT’s principal tenet is that it should be the starting point for semantic theory, too.