This volume documents the final eighteen years of William Penn's life, from 1701 to 1718. It opens with his last months as resident proprietor of Pennsylvania-a moment of great importance in the political history of the colony. It ends with his death on 30 July 1718, after a lingering illness.

Volume III covers Penn's return to England, his appeal to James II to support religious toleration, his struggle to reestablish his position in England and to manage his colony in America, and his return to Pennsylvania in 1699.