Objective: The aim of this study was to determine the impact of the domestic care environment on the prevalence of potentially traumatic events (PTEs) and posttraumatic stress disorder (PTSD) among orphaned and separated children in Uasin Gishu County, western Kenya. Methods: A total of 1565 (55.5% male) orphaned and separated adolescents aged 10-18 years (mean 13.8 years, sd 2.2), were assessed for PTSD and PTEs including bullying, physical abuse and sexual abuse. In this sample, 746 lived in extended family households, 746 in Charitable Children's Institutions (CCIs), and 73 on the street. Posttraumatic stress symptom (PTSS) scores and PTSD were assessed using the Child PTSD Checklist. Results: Bullying was the commonest PTE in all domestic care environments, followed by physical and sexual abuse. All PTEs were commonest among the street youth followed by CCIs. However, sexual abuse was more prevalent in households than in CCIs. Prevalence of PTSD was highest among street youth (28.8%), then households (15.0%) and CCIs (11.5%). PTSS scores were also highest among street youth, followed by CCIs and households. Bullying was associated with higher PTSS scores and PTSD odds than either sexual or physical abuse. Conclusion: This study demonstrated differences in distribution of trauma and PTSD among orphaned and separated children in different domestic care environments, with street youth suffering more than those in CCIs or households. Interventions are needed to address bullying and sexual abuse, especially in extended family households. Street youth, a heretofore neglected population, are urgently in need of dedicated mental health services and support.