“This guidance letter is intended to encourage the integrated use of trauma-focused screening, functional assessments and evidence-based practices (EBPs) in child-serving settings for the purpose of improving child well-being. The Department of Health and Human Services’ (HHS) Administration for Children and Families (ACF), Centers for Medicare & Medicaid Services (CMS) and Substance Abuse and Mental Health Services Administration (SAMHSA) are engaged in an ongoing partnership to address complex, interpersonal trauma and improve social-emotional health among children known to child welfare systems. We look to state and tribal governments to further this important work” (p. 1). Sections of this guidance letter include: introduction to the issue of complex trauma; the interplay between child trauma and psychotropic medications; components of a cross-system approach for promoting child well-being-integrating screening, assessment, referrals, and interventions; financial resources for addressing child trauma-child welfare, mental health and substance abuse, and Medicaid; quality impact of addressing child trauma.