Vocabulary control tools are used to control the terms used in indexing and information retrieval. These are natural language tools. Classification schemes, being tools for organizing information, could be of great help for vocabulary control – but the main body of a classification scheme uses a system of notation, an artificial language, whereas for vocabulary control we need natural language representation. Subject heading lists and thesauri are therefore used as vocabulary control tools for indexing printed and electronic information resources. This chapter begins with a discussion of the concept of vocabulary control tools, and outlines their typical features. It then considers the attributes of subject heading lists and describes the essential features of the most widely used one, the LCSH (Library of Congress Subject Heading list). It then goes on to outline the essential characteristics of thesauri and their role in information organization and retrieval, and illustrates this with examples from some online thesauri. The chapter then considers the role played by subject heading lists and thesauri in the organization and retrieval of electronic information, with examples from some special digital collections and subject gateways, especially the Intute subject gateways in different disciplines.