Mentalizing, the fundamental human capacity to understand behavior in relation to mental states such as thoughts and feelings, is the basis of healthy relationships and self-awareness. A growing evidence base supports the effectiveness of mentalizing-focused interventions in the treatment of borderline personality disorder. This volume explores wider applications, construing mentalizing as a core common factor in the effectiveness of psychotherapeutic interventions that cuts across treatment modalities and theoretical approaches ranging from psychodynamic to interpersonal and cognitive therapies. This book distills the burgeoning literature on mentalizing for clinicians of diverse professional backgrounds. The book is divided into two parts: Understanding Mentalizing fully explicates the concept of mentalizing and its foundations in developmental research and social-cognitive neuroscience; Practicing Mentalizing presents the general principles of psychotherapeutic interventions that promote mentalizing as well as a range of current clinical applications. Mentalizing is multifaceted -- for example, pertaining to self and others as well as explicit and implicit processes -- and links to myriad overlapping concepts including empathy, metacognition, theory of mind, mindfulness, and psychological mindedness. Two sides of research on the development of mentalizing in attachment relationships have significant clinical implications: interactions in secure attachment relationships enhance mentalizing and illuminate the conditions of optimal psychotherapeutic relationships; conversely, trauma in attachment relationships undermines the development of mentalizing and eventuates in developmental psychopathology that poses special challenges for psychotherapy. Neuroimaging is illuminating diverse brain regions that contribute to mentalizing capacity, including a "mentalizing region" in the medial prefrontal cortex that is consistently activated in mentalizing tasks; concomitantly, research on autism and psychopathy attests to the neurobiological basis of psychopathologies in which stable impairments of mentalizing are most conspicuous. In development and in psychotherapy, mentalizing begets mentalizing, as exemplified by a mentalizing stance that fosters inquisitiveness and curiosity about mental states in oneself and others; basic principles and clinical examples, including the use of transference, demonstrate the spirit and technique of mentalizing, capped off by a patient's first-hand account of mentalization-based treatment for borderline personality disorder. Attachment trauma is the wellspring of disrupted mentalizing capacity, and a focus on mentalizing provides an integrative framework for psychodynamic and cognitive-behavioral treatment of trauma as well as for parenting, family, and social-systems interventions directed toward interrupting the perpetuation of trauma in relationships. Psychoeducational interventions, including patient education and structured exercises, are employed to cultivate a therapeutic alliance around mentalizing; the book includes a straightforward explanation clinicians can use with patients, "What is Mentalizing and Why Do It?" In the chapter on mentalizing interventions, the authors propose to clinicians, "You are already doing it." If the effectiveness of treatment depends on therapists mentalizing and helping their patients do so more consistently and skillfully, clinicians of all persuasions can benefit from the extensive knowledge now available to hone further their attention to this vital therapeutic process.