Fire setting is one of the most challenging behaviors for the child welfare system. However, existing knowledge about its prevalence and correlates has been limited to research on single programs. The Illinois Department of Children and Family Services initiated a uniform assessment process at entry into state custody using a trauma-informed version of the Child and Adolescent Needs and Strengths (CANS). By using information from these assessments it is possible to establish an estimate of the prevalence of fire setting behavior and identify clinical and functional correlates. A review of 4,155 children and youth entering state custody reveals an overall prevalence rate of 1.35%. However, the rate for children and youth, 10 years and older was 3.5%. The rate was higher for boys than girls but there was no relationship to race. In general, the children and youth who engaged in fire setting behaviors had much higher levels of needs, fewer strengths, and were lower functioning. Within group analysis suggests the children and youth who set fires represent a relatively homogeneous group. (Contains 3 tables.)