'That very great play, Pericles', as T. S. Eliot called it, poses formidable problems of text and authorship. The first of the Late Romances, it was ascribed to Shakespeare when printed in a quarto of 1609, but was not included in the First Folio (1623) collection of his plays. This bookexamines rival theories about the quarto's origins and offers compelling evidence that Pericles is the product of collaboration between Shakespeare and the minor dramatist George Wilkins, who was responsible for the first two acts and for portions of the 'brothel scenes' in Act 4. Pericles serves asa test case for methodologies that seek to define the limits of the Shakespeare canon and to rdentify co-authors. A wide range of metrical, lexical, and other data is analysed. Computerized 'stylometric' texts are explained and their findings assessed. A concluding chapter introduces a new techniquethat has the potential to answer many of the remaining questions of attribution associated with Shakespeare and his contemporaries.