This text focuses on the need for a formal lexical theory, in particular one in which lexical insertion occurs at three derivational levels. Its syntactic, subcategorization-based approach fully analyzes constructions such as causatives, light verbs, nominalization, null arguments, passives, perfects, and pseudo-partitives. Rich empirical treatments based on English, French, Italian and Japanese further claim that morphology should be fully integrated into syntax. Theoretical constructs of Economy and Abstract Case are reformulated as conditions at three interfaces: the Dictionary, Logical Form and Phonological Form.