There is a great deal of disagreement about the definition and therapeutic value of an analytic process (AP). Does it exist? If it does, how to determine its presence, how to measure it, and in what kinds of treatments does it occur? In this article I highlight some of the literature from the "classical" school (such as by members of a COPE Study Group from the American Psychoanalytic Association (Committee on Psychoanalytic Education)), as well as from Theodore Jacobs, whom I consider to be an intermediate figure, and members of the "relational/interpersonal" school: Philip Bromberg, Edgar Levenson, and Donnel Stern. This selective review reveals three broad conceptualizations of the AP. It occurs (1) within the patient and is understood by the analyst via the patient's words; (2) within the patient as revealed to the analyst both by the patient's words and actions as well as by the analyst's understanding of his or her own subjective experience in response to the analysand; and (3) as a result of the real interaction between patient and analyst, and not as a result of the vicissitudes of the patient's transferences. All of these conceptualizations maintain that the AP can only be observed in the flow of what occurs between analysand and analyst over a period of time. Some empirical measures, which assess the presence or absence of an AP are noted. Yet, they are not generally employed in theoretical or clinical discussions, including supervision. Four decades ago, Brian Bird noted that "conclusions [about the analytic process] stem more often from assertions than from evidence and reasonable inferences." This article emphasizes that analysts need to integrate systematic empirical studies with clinical approaches.