This report was written in response to House Report 110-181, accompanying H.R. 2638, the Department of Homeland Security Appropriations Bill, 2008. In accordance with direction in that report, we are reporting on the operation of the transportation security inspector (TSI) program since it has been located at the Transportation Security Administration (TSA) within the Department of Homeland Security, including the size of the TSI workforce, the roles and responsibilities of TSIs, and the extent to which TSA has a reasonable basis for determining the size of the workforce needed to achieve inspection goals.