Such literary personages as Nathanael West, Maxwell Perkins, and Margaret Mitchell appear in Call It Experience, as does Margaret Bourke-White, with whom he collaborated on a number of projects and whom he also married. Including a self-interview, Call It Experience offers a wealth of insights into Caldwell's imagination, his sources of inspiration, and his writing habits, as well as his views on critics and reviewers, publishers, and booksellers. It is a source of both information and inspiration to aspiring writers.

Reverend Ira Sylvester Caldwell's missionary work took him and his family deep into the region commonly referred to as the Bible Belt. His son, Erskine, was at his side on innumerable home visits with the elderly, sick, and poor of Georgia, the Carolinas, Tennessee, Virginia, and Florida. By the time the younger Caldwell left home at seventeen, he had also witnessed such varieties of religious experience as "Church of God all-night camp meetings, Holy Roller exhibitions on splintery wooden floors, primitive Christian baptismal immersions in muddy creeks, Seventh-Day Adventist foot-washings, Body of Christ blood-drinking communions, Kingdom of God snakehandlings, Full Redeemer glossolalia services, Fire Baptized Holiness street-corner rallies, Catholic mass at midnight on Christmas Eve, the rituals of Jewish synagogues, and . . . philosophical lectures in Unitarian churches."

Decades later, Caldwell drew on this fertile background when he toured Georgia and neighboring states in order to hear firsthand from ministers and churchgoers about how southern Protestantism was faring amid the social upheaval of the mid-1960s. Deep South offers a rich mix of anecdotes, memories, interviews, and observations that point to what may be the true essence of southern spirituality.

Caldwell lets the poor speak for themselves. Supported by his commentary, they tell how the tenant system exploited whites and blacks alike and fostered animosity between them. Bourke-White, who sometimes waited hours for the right moment, captures her subjects in the shacks where they lived, the depleted fields where they plowed, and the churches where they worshipped.