While dozens of books pedantically list correct rules of usage and grammar, Deciding Usage details the evolution of forms, such as It is I and It is me, and supplements this history with a survey of textbook definitions of correct usage with the ultimate goal of empowering people to make their own informed decisions. Sherwin treats the study of language as a humane discipline; consequently, he sees it is an inquiry into the language behavior of people described by the Pope as the 'glory, jest and wonder of the world,' rather than the application of a set rules to the structure of English. Deciding Usage was originally designed for English teachers and their students, but will be of interest to any one who has ever wanted to know not just why a particular usage was correct, but why it was so.