In this paper we will extend Smith's (1997) two-component aspect theory to develop a two-level model of situation aspect in which situation aspect is modelled as verb classes at the lexical level and as situation types at the sentential level. Situation types are the composite result of the rule-based interaction between verb classes and complements, arguments, peripheral adjuncts and viewpoint aspect at the nucleus, core and clause levels. With a framework consisting of a lexicon, a layered clause structure and a set of rules mapping verb classes onto situation types, the model is developed and tested using an English corpus and a Chinese corpus.