The Proper Treatment of Events offers a novel approach to the semantics of tense and aspect motivated by cognitive considerations. The book begins by presenting data about the human conceptualization of time, proposing that planning is important in this regard, and hence equally for the linguistic encoding of time as tense and aspect. It then introduces a formal theory of planning, a combination of an event calculus as developed in Artificial Intelligence with a truth theory and logic programming techniques. The combined system is then applied to detailed analyses of tense, grammatical and lexical aspect, coercion, and different types of nominalizations.