The problem which I wish to consider is the problem of deciding whether the protestant reformation was a revolution. The problem should be of interest to a number of different scholars. There is no obvious reason, however, why it should interest those who define themselves primarily as ecclesiastical historians. I believe, however, that there is an ecclesiastical dimension to this problem and that earlier work upon it is flawed by a failure to recognize that fact. I see these flaws even in the work which has most stimulated my own recent thinking on the problem. This is the work of a number of modern english historians and above all a book published by that great english contribution to the american community of historians, Lawrence Stone, titled The Causes of the English Revolution, 1529–1642. I found particularly useful Stone’s lengthy analysis of the phenomenon of revolution, borrowing extensively from the recent work of political scientists, sociologists, and other behavioral scientists. And I found persuasive his application of that analysis to the puritan revolution. I found his ultimate conclusion, however, ‘that the crisis in England in the seventeenth century is the first “Great Revolution” in the history of the world,’ to be nonsense. It is nonsense partly because he has ignored the illumination which can be shed on this topic by a consideration of ecclesiastical history. I shall argue that the protestant reformation of the early sixteenth century was also a revolution, anticipating Stone’s by more than a hundred years. And I shall seek to demonstrate this argument with evidence drawn from ecclesiastical history.