One of the most intriguing aspects of Tozer’s ministry is the extent to which he drew from the writings of medieval Catholic mystics. In fact, twenty-eight of the thirty-five books on his recommended reading list were written by Catholics who lived either during or soon after medieval times. Needless to say, this is not something people would normally expect from a pastor in the Christian and Missionary Alliance. Nevertheless, Tozer appears to have been profoundly influenced by these writers and developed a deep appreciation for them. This dissertation argues that while A. W. Tozer had a number of notable mystical tendencies, his spiritual insights are demonstrably within confessional evangelical boundaries. In other words, he drew deeply from the well of medieval Catholic mysticism but was, in the end, successful in maintaining his confessional evangelical identity and values. He was nourished by what he viewed as true and carefully discarded the rest. Furthermore, in demonstrating Tozer’s confessional evangelical identity, this dissertation also describes the distinct contours of his thoughts about various matters central to evangelicalism. And to conclude, the dissertation considers how Tozer is a model of how Christians can be uncompromising in their doctrinal convictions and yet benefit from a wide variety of spiritual writers, even those of other traditions.