Without a doubt, the Heidelberg Catechism has been the most beloved confessional symbol of the Reformed Churches since it was first published in 1563. But who wrote it? And what was the theology of its authors? In his Ph.D. dissertation, Dr. Walker argues that, while Zacharias Ursinus appears to have been its primary author, many others, including Caspar Olevianus and Elector Frederick, made significant contributions. Further, in composing the Catechism, the authors drew from countless sources (both ancient and contemporary), resulting in an instructional tool that expresses the beauty of the Reformed faith while remaining Biblically ecumenical.