This study deals with the Welsh revival movement of the 18th century and the remarkable way that George Whitfield fitted into it. Whitfield was a Calvinist who believed that one could be both a Methodist and a Calvinist. The leaders of the Welsh revival were also Calvinistic and welcomed him. The text traces the beginnings and development of the movement, carrying it up to the present day and showing changes in beliefs. A pocket of Welsh immigrants brought that church to America in upstate New York, where it later (in the 1920's) united with the Presbyterians.