Negation gives rise to complex issues of syntactic polarity marking and directionality of monotone inference, and forces certain decisions in the semantics. Polarity is of great practical importance in computing entailment. This chapter explains how polarity-marked strings can be derived monotonically and in a single pass. It looks at examples of polarized determiners, such as the singular existential some, and considers categories for some that impose positive polarity on the raised argument. The chapter also analyzes the universal quantifier determiners every and each and their relatives, which are syntactically polarized similarly to some. Finally, it discusses indefinite determiners, the polarity of pronouns, multiple negation, negative-concord dialects of English, and negative scope and coordination.