The purpose of this study is to set forth the attitude toward the English government, in one of the most troubled periods of its history, of two religious bodies which by a large number of their contemporaries were considered enemies of all government, and sworn foes of peace and order. Twice in a period of six years the men belonging to these two parties were actually in a position to affect the policy of the government; for part of the period one of them practically controlled Ireland, and throughout the Protectorate they were a serious problem to Cromwell. I have endeavored to ascertain as far as possible to What extent the political programs of the two parties furnished justification of the popular opinion concerning them, and, in couse quence, what was their real importance in the history of their time.