Children who have been placed in foster care have been found to be at a high risk of having a medical, social or behavioral disability. This brief, one in a series of briefs addressing access to services for children in the child welfare system, examines Supplemental Security Income (SSI) eligibility among children living in out-of-home placements in the child welfare system, using data from the National Survey of Child and Adolescent Well-Being. The analysis indicates that a large number of children living in foster care may be eligible for SSI. The rates of SSI eligibility we estimate vary depending on children's age, race/ethnicity, gender and locality of placement. (Contains 4 tables and 11 notes.)