Background: Anxiety disorders are garnering increasing attention for their contribution to high-risk issues and functional impairment. Adolescents are typically admitted to partial hospitalization programs (PHPs) due to high-risk presentations. However, the frequency of anxiety disorders in PHPs is not well-established, in part because anxiety can be overlooked in acute settings due to limited lengths of stay and focus on stabilization. Objective: This study aims to evaluate the frequency and severity of anxiety disorders among a sample of adolescent PHP patients to assess the need for anxiety-specific assessment and interventions in higher acuity settings. Methods: Participants were 158 youths ages 13 to 19 years old (M = 15.49 years, SD = 1.50) who were admitted to an adolescent PHP and their caregivers. Clinician-reported diagnostic information was collected from the youth's electronic medical record, and self- and caregiver-rated severity of anxiety was collected using the Screen for Child Anxiety Related Emotions Disorders (SCARED-C/P). Frequency of anxiety and related disorder diagnoses and self- and caregiver-reported severity were assessed using descriptive statistical methods. Results: 75% of participants were diagnosed with an anxiety disorder (n = 118). On average, participants with anxiety disorders had elevated SCARED-C scores. Youths with depressive disorders had elevated SCARED-C scores even when they did not carry anxiety disorder diagnoses. Caregiver ratings of the youth's anxiety symptoms on the SCARED-P were elevated when youths had anxiety disorders. Conclusions: These findings suggest that anxiety is common in an adolescent PHP setting and support investing in evidence-based assessment and treatment of anxiety in high-acuity settings.