This report addresses states' definitions and assessment guidelines for the category of traumatic brain injury, newly identified as a disability under the Individuals with Disabilities Education Act. Information sources included state policy documents from 19 states and interviews with state education agency personnel. A background section discusses the federal regulations pertaining to traumatic brain injury. A section on findings compares states' definitions to the federal definition, reports on how states determine eligibility for special education services, and notes the potential for litigation concerning identification of students. The study concludes that states are prepared to identify and appropriately serve children and youth with traumatic brain injury. State agency personnel recognize the need to provide local districts with the training and information for effective decision making regarding students with traumatic brain injury, and expressed a need to obtain resource guides and inservice training materials for distribution to local education agencies. Six selected resources are listed. (JDD)