This report presents the results of a Preliminary Assessment (PA), conducted by Environmental Resources Management, Inc. (ERM), of Camp Roberts, a California Army National Guard (CA ARNG) installation. This PA was conducted to characterize the site accurately and determine the need for further action. This PA satisfies the requirements of the U.S. Army Installation Restoration Program (lRP) and the U.S. Environmental Protection Agency's (EPA) Guidance for Performing Preliminary Assessments Under CERCLA, dated September 1991. Camp Roberts is a 42,363 acre active CA ARNG training installation located in San Luis Obispo and Monterey counties, California, used for training military units from the western United States. This PA identified fifteen (15) environmentally significant operations (ESOs); i.e., sites identified as known or potential sources of CERCLA contaminant releases. There are numerous known and suspected petroleum releases believed to have been relatively minor and most probably covered by the CERCLA petroleum exclusion. Site investigations to identify and characterize possible CERCLA releases, and to determine the need, if any, for remedial action, should be conducted at the following areas: Engineering Yard; Ranges Y39 and M40; UDLP buried drum area and Ranges 5, 12 and 18. Immediate corrective action must be taken regarding the open storage of PCB transformers.