The notion of focus structure in this work refers to the distinction between categorical, thetic and identificational sentences. The central claim is that the syntactic representation of every sentence has to encode which of these types of focus structure is realized. This claim is discussed in great detail with respect to syntax, intonation and semantics within the framework of the Minimalist Program. It is shown that the incorporation of focus structure into syntax offers new perspectives for a solution of vexing problems in syntax and semantics. For example, fronting (preposing,...