Objectives: This study is focused on how architectural design of adolescent psychiatric hospitals could positively affect not only patients but also staff members working at the hospitals. Background: Adolescents between the ages of 12 and 18 are among the young population with the highest percentage of mental illness. However, there are limited number of intentionally designed psychiatric hospitals for adolescents. Staff who work in adolescent psychiatric hospitals may face workplace violence. Studies on environmental impacts suggest that the built environment affects patients’ well-being and safety as well as staff’s satisfaction, working condition, safety, and health. However, there are very few studies that focus on adolescent psychiatric hospitals and the impact of the built environment on both staff and patients. Methods: Data were collected through literature analysis and semi-structured interviews with staff of three psychiatric state hospitals with adolescent patient units. The triangulation of multiple data sources informed a set of environmental design conditions that captures the complexity and connectedness of architectural design and the occupants of an adolescent psychiatric hospital. Results: The results present architectural composition, atmosphere, lighting, natural environment, safety, and security as indispensable design conditions to create an enclosed and city-like campus that provides a serene, secure, and structured environment that benefit staff and adolescent patients. Conclusion: The specific design strategies that need to be incorporated in the architectural design of a safe and secure adolescent psychiatric hospital include an open floor plan that respects patients’ autonomy and offers privacy while always providing staff with full visibility of patients.