Discovering Therapeutic Efficacy brings together selected papers and book chapters by Howard Bacal, spanning 40 years as a psychoanalyst, psychiatrist, and psychotherapist. The book includes several key pieces of writing influenced by psychoanalytic figures Bacal had the rare opportunity to study under including Michael Balint, Wilfred Bion, Heinz Kohut, Marion Milner, J. D.  Sutherland, and Donald Winnicott. The chapters variously describe how the concept of optimal responsiveness is pivotal to the uniqueness of therapeutic need and how each psychoanalytic dyad discovers its unique capacity to implement it.  Bacal describes how this led him to develop specificity theory, a process theory of therapeutic possibility. Discovering Therapeutic Efficacy is replete with illustrative clinical examples. It will be of great interest and of practical usefulness not only to psychoanalysts, but to every practitioner of dynamic psychotherapy as they strive to be as optimally responsive as they can to their patients and students. The free Open Access version of this book, available at http://www.taylorfrancis.com, has been made available under a Creative Commons Attribution-Non Commercial-No Derivatives (CC-BY-NC) 4.0 license.