The complications of usage in general dictionaries and the complications of dictionaries in specialized dictionaries of usage. Superficially, usage refers to “good usage” or correctness judgments about language variation, like lie vs. lay, and general dictionaries have tried to signal such judgments for some words. Yet usage also refers to “actual usage,” “contextual usage,” and “traditional usage,” which are all bound up with the simpler notion of “good usage.” The first part of this chapter elaborates these types of usage, the relationships among them, and the ways general dictionaries have incorporated all four types. The second part focuses on specialized dictionaries that focus exclusively on usage issues in all four senses. Such dictionaries vary widely in their macro-structures and micro-structures, and the chapter provides a framework for discerning elements within the entries. Dictionaries of usage are usually better than general dictionaries in giving detailed explanations and treating more issues and more kinds of issues. They do not seem to have improved on general dictionaries for identifying the most important usage issues to be aware of.