Cassel Hospital, located at 1 Ham Common, Richmond, Surrey, is a part of the West London NHS Trust. Established in 1919, the hospital specializes in the treatment of severe and complex personality disorders. It provides both inpatient and community-based outreach programs, offering long-term therapeutic care designed to help patients who have often exhausted other avenues of mental health support. The hospital combines psychosocial and psychoanalytic treatments within a therapeutic community framework.

Cassel Hospital's primary specialty is in the treatment of personality disorders, offering comprehensive services including:

• Inpatient Services: Long-term residential treatment for severe personality disorders.
• Outreach Services: Community-based treatment programs.
• Therapeutic Community: Integrated psychosocial and psychoanalytic therapy.
• Research and Training: Conducting research and providing training for professionals in the field of mental health​.

Cassel Hospital is committed to maintaining high standards of care and is regularly inspected by the Care Quality Commission (CQC). The hospital adheres to rigorous protocols to ensure patient safety and the effectiveness of its treatment programs. Continuous audits and patient feedback are integral to the hospital’s quality assurance practices.

The vision and mission of Cassel Hospital align with those of the West London NHS Trust: to provide high-quality, compassionate care tailored to the needs of individuals with severe and complex personality disorders. The hospital aims to improve patients' quality of life through evidence-based treatments and to foster a therapeutic environment that supports recovery and personal growth.

Cassel Hospital is recognized for its pioneering work in the treatment of personality disorders. As a national service, it is known for its innovative therapeutic approaches and contributions to mental health research. The hospital has received positive evaluations from healthcare regulators and maintains a strong reputation within the mental health community​.