A concise, clinically oriented introduction to the concept of mentalization that explains how the capacity to understand one’s own and others’ mental states develops in attachment relationships, how disruptions contribute to emotional dysregulation and interpersonal problems, and how mentalization-based principles can guide assessment and psychotherapy. The text combines theory with practical examples—therapeutic stance, strategies to strengthen reflective function, and case vignettes—to help clinicians and students apply mentalizing techniques to improve emotion regulation, relationship functioning, and treatment outcomes.