This article provides an overview of Parent-Child Interaction Therapy (PCIT), a manualized intervention for young children with externalizing behavior problems, which untreated can evolve into more severe psychopathology. With its unique approach incorporating play therapy elements and live caregiver coaching, PCIT is grounded in attachment and social learning theories. We describe its structure, course, and goals, as well as the strong research base supporting the efficacy of PCIT, including with different populations (e.g., diagnoses, at-risk), settings (e.g., clinic, school), and delivery formats (e.g., individual, group, telehealth). We also provide an overview of new directions and variations of PCIT.