Background:
Child and Youth Welfare Service (CYWS) facilities are an essential source of support and recovery for unaccompanied young refugees (UYRs) with traumatic experiences. Their mental health is affected by pre-, peri-, and post-flight stressors, with the residential setting playing a crucial role in increasing or reducing these risks.

Objective:
This longitudinal study aimed to analyze how institutional factors in CYWS facilities influence UYRs’ mental health over a one-year period.

Participants and setting:
We included N = 131 UYRs (Mage = 17.04; SDage = 1.46; 81.7 % male) living in N = 22 residential group homes in Germany.

Methods:
Standardized questionnaires were used to assess posttraumatic stress symptoms (PTSS), depression, and anxiety symptoms. Additionally, facility directors or social workers completed a questionnaire on facility characteristics, and the research team evaluated workload, staffing, and accommodation quality.

Findings:
Lower staff workload predicted lower PTSS, depression, and anxiety scores among UYRs after one year. Living in UYR-specific groups also predicted lower PTSS scores. Open group climate after six months (T1) mediated the association between accommodation quality rating and PTSS, depression, and anxiety, as well as between UYR-specific group and PTSS and depression.

Conclusion:
The institutional environment has an important impact on UYRs’ mental health. An institutional environment with sufficient staff, a high accommodation quality, and UYR-specific groups is beneficial for reducing the mental health burden.