James Ussher was a highly prolific titan of publication in the seventeenth century, and his writings earned the esteem of many in the Reformed churches. Still, a mountain of his unpublished manuscripts remains in the archives, ripe for investigation and full of just as much insight as his published works. This volume collects three of Ussher’s most significant unpublished manuscripts, each covering the major topics of theology. With introduction and explanatory apparatus by Harrison Perkins, these documents are available for the first time in print and in translation, shedding fresh light on Ussher’s contribution to the Reformed tradition.