In his new book, A Brief Theory of Spycraft: Weaving the Tangled Web

Costanzo reveals the classic theoretical underpinnings of his profession in a modern context. The book is not for everyone. It is, in effect, a mini-textbook for students and it requires some concentration. But even if not for the casual reader, it will be of interest to many government employees, to security personnel, to anyone attuned to international relations, and to serious espionage buffs.

Costanzo is also the author of My CIA: Memories of a Secret Career, in which he describes what it was like to work in the CIA's Clandestine Service during the final decades of the Cold War, starting from his early training through his senior tours as a chief of station.