Despite the recognized importance of mental health concerns among youth in the child welfare population, data suggest a significant gap between children who need services and children who receive services. This paper aims to address this problem by focusing on the ways in which the system identifies--or fails to identify--children as needing mental health services. The paper reviews current guidelines, policies, and practices for mental health screening and assessment of youth in child welfare including available evidence-based screening instruments that have been evaluated in child welfare or other settings. It is concluded that the use of evidence-based screening and assessment instruments will improve the identification of children needing mental health services and offer the opportunity to provide appropriate care to children who are currently being overlooked. (Contains 1 footnote.)