This book is the first to argue that the Rival Poet of Shakespeare's Sonnets is the well-known young Elizabethan writer Richard Barnfield (1574-1620), long suspected to have been one of Shakespeare's "private friends" (as they were termed by Francis Meres in 1598), with whom (as Meres also tells us) Shakespeare shared some of his sonnets. This is also the first book to argue that William Stanley (1561-1642), sixth earl of Derby, is the young man to whom they addressed their respective sonnets and other love poems in the period c. 1592-1595. In making these identifications, this is the first book to examine in detail the dialogue between Shakespeare's Sonnets and three of Barnfield's books of poetry (all published within a little more than one year)--a dialogue only known to be discussed in a conference paper and one other book. William Shakespeare, Richard Barnfield, and the Sixth Earl of Derby will likely appeal to all readers interested in Shakespeare's life and love poetry, both specialist scholars and non-specialist enthusiasts alike.