This report presents the results of the preliminary assessment (PA) conducted by Argonne National Laboratory at the Arizona Army National Guard property near Florence, Arizona. Preliminary assessments of federal facilities are being conducted to compile the information necessary for completing preremedial activities and to provide a basis for establishing corrective actions in response to releases of hazardous substances. The principal objective of the PA is to characterize the site accurately and determine the need for further action by examining site activities, quantities of hazardous substances present, and potential pathways by which contamination could affect public health and the environment. Florence Military Reservation is a 5,655-acre site located in the southern portion of Arizona, about 65 mi southeast of Phoenix, in the county of Pinal. Florence Military Reservation includes Unit Training Equipment Site (UTES) 1, an artillery firing range, and ammunition storage. The subject of this PA is the UTES. The environmentally significant operations associated with the UTES property are (1) vehicle maintenance and refueling, (2) supply/storage of materials, and (3) the vehicle washrack.