The main goal of this chapter is to explain why natural language needs negative predicates to express negative contents. In contrast with syntactic negation, negative predicates exhibit some semantic properties, which are not expressed syntactically: they are complete semantically, restricted to lexical categories, and encode a negative feature. On the other hand, negative predicates are motivated pragmatically: they are stronger statements than syntactic negation; they realize, under syntactic negation, mitigated assertions; they cannot express metalinguistic negation, as syntactic negation does. One relevant semantic proposal (Horn 1989) is the distinction between two negation operators: ¬, realized syntactically, and ©, realized lexically. This chapter does not only give arguments supporting these properties, but also provides an explicit account of the relation between syntactic negation and negative predicates.