The Reign of King Edward III (1596) is a little-known Elizabethan play of uncertain authorship, some or all of which has long been considered possibly to have been Shakespeare's work. In assessing the origins of King Edward III, Slater's book is pioneering in its use and extension of vocabulary tests to solve problems of authorship. The author reviews the debate regarding the creation of King Edward III. Following a survey of applications of quantitative methods to literary problems, he examines the authorship of Edward III by means of a statistical study of the play's rare words, and their links with rare words in Shakespeare's canonical plays. This is a technique developed by Slater himself and is of particular interest to literary scholars and stylometrists. The investigation indicates that the play was written by Shakespeare. The book therefore provides important evidence to suggest that an exciting and much-neglected play should be admitted into the canon of Shakespeare's early history plays.