Purpose <p>To examine mental health symptoms and their associations with institutional and sociodemographic characteristics among school-aged children reunified with their families following deinstitutionalization in a country in the South Caucasus.</p> Methods <p>This study reports cross-sectional findings from baseline data collected for a randomized clinical trial (ClinicalTrial.gov #NCT05396625). The sample included 434 children (ages 7–12) with histories of institutional placement and 305 caregivers (parents or kin-relatives) recruited in Azerbaijan following family reunification. Individual- and family-level socio-demographic characteristics were examined to assess their associations with mental health outcomes, as reported by children (self-esteem, symptoms of depression, post-traumatic stress disorder/PTSD) and by caregivers (Attention-Deficit/Hyperactivity Disorder/ADHD symptoms, and internalizing and externalizing behavioral problems). Mixed effects regression models were employed to account for clustering of children within families.</p> Results <p>Over half (52%) of children with a history of institutional placement scored above the clinical cutoff for depressive symptoms on the Center for Epidemiologic Studies Depression Scale (CES-D), 37% for PTSD symptoms on the Child Revised Impact of Events Scale-8 (CRIES-8), and 36% for ADHD symptoms on the ADHD Rating Scale-IV. Caregiver reports on the Strengths and Difficulties Questionnaire (SDQ) indicated that 45% of children were at high or very high risk for emotional and behavioral problems, with internalizing (54.05%) more than twice as common as externalizing (24.54%). Middle school-aged children exhibited higher symptomatology across multiple mental health outcomes compared to those in elementary school, and children with special needs displayed elevated symptoms across all parent-reported outcomes. According to parent reports, girls showed fewer ADHD (-3.60, 95% CI: -5.80, -1.39) and externalizing (impulsivity, aggression, disruptive behaviors, -1.74, 95% CI: -2.60, -0.89]) but more internalizing symptoms (withdrawn, anxious, persistent sadness, low self-worth) than boys, while child-reported depression did not differ by gender. Lower socio-economic status (e.g., receipt of public assistance, perceived low SES, larger household size, residence outside the capital, and lower caregiver education) and maternal (vs. paternal or non-parental) reports were associated with higher parent-reported internalizing problems among children. Children who had stayed in boarding school-type institutions with weekend home returns showed fewer problems (-2.70, 95% CI: -5.10, -0.31), especially internalizing, than those from orphanages.</p> Conclusion <p>A substantial proportion of children reunified with families following deinstitutionalization exhibit clinically significant mental health symptoms. Mental health symptomatology varied by age, gender, and socioeconomic disadvantage, with the latter exerting a stronger influence on parents’ perceptions than on children’s self-reports. These findings underscore the importance of integrating targeted preventive mental health programs with supportive family-based interventions that also address socio-economic factors, in order to better support this vulnerable population during and after the reintegration process.</p>