Demand is steadily growing for language tests with a specialized focus which will suit the needs of key professional domains as diverse as business, law, the airline industry, and teacher education. This book explores the testing of language for sepcific purposes (LSP) from a theoretical and a practical perspective, with a particular focus on the testing of English for business purposes. A range of tests - both past and present - is reviewed, and the development of business English testing at Cambridge ESOL is discussed. The description of the revision of the Business English Certificates (BEC) forms a major part of the book and offers a unique insight into an approach to large-scale ESP test development and revision.