This fact sheet provides data on infants, toddlers and young children who are experiencing high stress as a result of a number of risk factors specifically identified in the Individuals with Disabilities Education Improvement Act of 2004 (IDEA 2004), including substantiated abuse or neglect, foster care placement, homelessness, exposure to family violence and prenatal exposure to drugs or alcohol. It begins by highlighting several factors that have been found to maximize the likelihood of promoting positive outcomes for all vulnerable young children and their families. Subsequent sections provide data on specific populations of at risk children.