There are two motives for this study. First and foremost is the spiritual inspiration which was anticipated in a comprehensive examination of the writings or this great Christian Churchman. Coupled with the spiritual values was the corresponding intellectual stimulation or exploring in a relatively new field to this writer. It soon became evident that though great scholars had blazed the trail, still much original research was required. All of this was done with the purpose of more clearly understanding seventeenth and eighteenth century English and American history. The problem of this study is to define clearly the thought of William Perkins, and to realize how it was applied to sixteenth and seventeenth century Christians. This is what is meant by his activity. Since the emphasis is placed upon his thought it was considered best not to make an extensive study of his influence on the Continent and in America. That in itself is a topic of major research. Suggestions of his influence are given in the final chapter which indicate to some extent the application of his thought following his death.