Tense, Aspect and Modality are often discussed in terms of morphology, syntax, semantics, grammaticalization and typology and they are known to interact in predictable ways. The course reviews a number of issues involved in the cross-linguistic description of TAM systems and raises a number of theoretical questions that relate to their syntactic properties in English and across languages. Crucial questions include: •the asymmetries observed between formal and functional distinctions; •the nature of TAM categories and super-categories, including their ‘syntactic relevance’; •the precise syntactic level at which different TAM categories seem to be relevant (e.g. the VP, the IP or the CP domain); •various approaches to cross-linguistic comparability and the plausibility of universal inventories in the TAM area.