Although advances in neuroscience have dramatically reshaped knowledge about psychiatric medications in children and adolescents, the textbooks available to clinicians have—until now—failed to keep pace, forcing readers to choose between resources devoted to neurobiological mechanisms or those focused on clinical application. Textbook of Pediatric Psychopharmacology: Neurodevelopmental and Biopsychosocial Bases and Clinical Practice closes that divide, offering researchers, clinicians, and trainees a single resource that bridges molecular science and the human realities of clinical care. Across 70 chapters, this textbook covers the molecular pharmacology of every major psychotropic class and the psychosocial and cultural factors that shape the outcomes that matter most to young patients and their families. Condition-specific sections provide evidence-based guidance on assessment and treatment across the full range of pediatric psychiatric presentations, from ADHD and autism to mood, anxiety, eating, and substance-related disorders. The authors also look beyond conventional pharmacology to emerging treatments—including psychedelics and endocannabinoid modulators—that are gaining momentum in psychiatric research and practice. Dedicated sections address populations that standard texts often overlook, such as medically ill children, adolescents with intellectual disability, pregnant and postpartum teens, and youth with gender-incongruent experiences. Drawing on the expertise of dozens of contributors from research, clinical practice, and lived experience across institutions and disciplines, Textbook of Pediatric Psychopharmacology reflects not only the current state of scientific knowledge but also the nuances, uncertainties, and ongoing debates that characterize the field. Yet the focus throughout returns to the same place: the children and adolescents being cared for and the profession's responsibility to get it right.