The U.S. Department of Homeland Security, Office of Domestic Preparedness identified the need to examine and classify various types of vulnerability assessment methodologies, software, and tools as they would pertain to different types of assets. This Phase I study focused on the methodologies used to determine vulnerabilities and risks, which in turn, identify countermeasures that could be effective at reducing the risk by reducing the vulnerability. In identifying physical asset vulnerability assessment providers using a proven methodology, this study's goals were to develop criteria for analysis of various methodologies, clearly map capabilities and identify any capability overlaps, describe advantages and disadvantages of using particular methodologies, automated tools, software and emerging technologies to assess different types of assets, and to provide evidence that methodologies, automated tools, software and emerging technologies can perform as advertised. Forty-four private methodologies were considered in this study. Sufficient information was found to make some level of assessment for 24 public (Federal, State, and local government) methodologies. Study findings drawn from this analysis include: (1) the most robust methodologies do not solely focus on one sector of the economy; (2) the quality of the assessor in all cases is very important; (3) while all methodologies determined some measure of risk, few methodologies actually calculated a numerical value for that measure of risk; and (4) the training required to accurately use one of these methodologies varied greatly in time and cost. Additional phases of this project were recommended to better determine the effectiveness of the various methodologies. Appendices A-D