In Economy and Semantic Interpretation, Danny Fox investigates the relevance of principles of optimization (economy) to the interface between syntax and semantics. Supporting the view that grammar is restricted by economy considerations, Fox argues for various economy conditions that constrain the application of "covert" operations.Among other things, he argues that syntactic operations that do not affect phonology cannot apply unless they affect the semantic interpretation of a sentence. This position has a number of consequences for the architecture of grammar. For example, it suggests that the modularity assumption, according to which a language's syntax must be characterized independently of its semantics, needs to be revised. Another consequence concerns new answers to the question of exactly where in the syntactic derivation the various constraints on interpretation apply.