This work is structured as follows. Section 2 introduces the compositionality principle, presents different types of compositionality violations, and briefl y outlines the existing approaches to type shifting. Section 3 presents the main tenets of the Generative Lexicon theory: the concept of underspecifi cation (§ 3.1), the structure of the lexical entry (the levels of representation are reviewed in § 3.2.1, the lexical-semantic types are dealt with in § 3.2.2), and the general approach to selection within the predicate (§ 3.3). Section 4 provides a detailed description of the selectional mechanisms assumed in the Generative Lexicon: § 4.1 focuses on type matching, § 4.2 on accommodation, and § 4.3 on coercion. Section 5 sums up the fi ndings of the previous sections and refl ects on their implications for the compositional treatment of different kinds of word combinations.