Partial hospitalization programs (PHPs) and other acute mental health treatment programs, which are becoming increasingly common, may help divert children and adolescents from inpatient psychiatric care and provide a concentrated dose of intervention to individuals living in low-resource areas. However, there have been relatively few examinations of the effectiveness of PHPs in addressing emotional concerns (e.g., anxiety, depression, irritability) and functional impairment in youth. Further, evidence-based treatments originally designed for delivery in an outpatient weekly format may require significant adaptation to be appropriate for delivery in acute mental health settings, which differ significantly from weekly outpatient care in program structure, patient acuity, and staffing. In this intervention development and adaptation report, we present the rationale for adapting a transdiagnostic approach to treating emotional disorders—the Unified Protocols for Transdiagnostic Treatment of Emotional Disorders in Children and Adolescents (UP-C/A)—for a hospital-based, general psychiatric partial hospitalization program. We use implementation science frameworks to describe our iterative approach to treatment adaptation and testing and to describe in detail proactive, planned adaptations to the UP-C/A for partial hospitalization that occurred prior to initial implementation and pilot testing. Three case examples (child, preadolescent, adolescent) are presented to illustrate how a transdiagnostic approach to care such as the UP-C/A can be used intensively in an acute mental health setting to address emotional and behavioral concerns, including safety.