The Arden Encyclopedia of Shakespeare's Language is the first comprehensive account of Shakespeare's language to use computational methods derived from corpus linguistics - methods of choice for today's historical linguist. This third volume focuses on keywords in Shakespeare's plays. Play keywords are derived by conducting a statistical comparison between the words in one play with those in all the other plays. For characters, the statistical comparison is made between the vocabulary of one character and that of all the other characters in the same play. These keywords are then used to create 'linguistic profiles' of each play and main character. The profiles show how patterns of words around keywords contribute to themes in plays and characterization of the protagonists. For example, we reveal how the simple word 'Goodnight' contributes to dramatic tension in Julius Caesar, or how in Romeo and Juliet, Juliet's most distinctive yet apparently innocuous words, 'if', 'yet' and 'but', create an important aspect of her character.