Mentalization is a relatively new but extremely powerful concept in psychoanalysis. It bridges the neurobiological foundation of behavior, its evolutionary significance, and its developmental origins, and is central to our understanding of affect regulation and effortful control. It has also sparked a fruitful dialogue between the philosophy of mind, developmental psychology, and psychoanalysis. Most directly, it has brought together psychoanalytic theorists, researchers, and clinicians in a mutually enriching interaction, leading to new therapeutic approaches and new ways of understanding the mechanisms of action in familiar models. Fredric Busch has done an excellent job in this collection of theoretical, research, and clinical studies by bringing together key figures in the field, complemented by overviews from Otto Kernberg, Mary Target, and Busch himself.