All languages contain grammatical markers of tense and/or aspect (MTAs). Linguists who analyze tense and aspect from a functional point of view may define the meanings of MTAs in cognitive terms (Janssen 1996) or in terms of their discourse functions (Benveniste; Weinrich; Waugh; Hopper) and do not necessarily view their use and interpretation as dependent in the first instance on their semantics, as do the majority of linguists studying tense and aspect, who adopt a formal point of view from which tense and aspect are seen as basically referential categories. The assumptions of this formal, referential approach underlie most of the discussion in this essay, though in certain areas functional analyses have played a central role. To fully interpret a spoken discourse or written text, a considerable amount of content must be filled in (Carston, 1998). Pragmatic factors, including cotext (the discourse preceding, or the text surrounding, the material to be interpreted) and context, play a crucial role in enriching the bare-bones content provided by the semantics. In functional theories of tense and aspect, pragmatics may in fact be seen to underlie the semantics.