 Generalized quantifiers are now standard equipment in the toolboxes of both logicians and linguists. The purpose of this entry is to describe these tools: where they come from, how they work, and what they can be used to do. The description is by necessity sketchy, but several more comprehensive surveys exist in the literature and will be referred to when appropriate. To fully appreciate the text below, basic familiarity with elementary set theoretic terminology, and with the language of first-order logic will be helpful.