Over the past decade, attribution scholars have come to a consensus that Shakespeare wrote some of the additions printed in the 1602 quarto of Kyd's Spanish Tragedy. This new development in textual studies has far-reaching consequences for established theatre-historical narratives. Accounting for Shakespeare's involvement in The Spanish Tragedy requires us to rethink the history of two major theatre companies, the Admiral's and the Chamberlain's Men, and to reread much of the documentary record of late Elizabethan theatre. Modelling what a theatre-historical response to new attributionist arguments might look like, the author offers an in-depth reinterpretation of Philip Henslowe's records of new plays, develops a novel account of how theatre companies copied and adapted plays in one another's repertories (including a reconsideration of the 'Ur-Hamlet' and the two Shrew plays), and reconstructs an early modern cluster of Hieronimo plays that also allows us to reimagine Ben Jonson's career as an actor.