In 2009, the US Department of Homeland Security (DHS) began using a targeted questionnaire to produce individual vulnerability/protective-measure values for high-risk critical infrastructures and key resources. As sites continue to be assessed, the topic of resilience is emerging as a necessary focus in risk management and infrastructure protection. Enhancing the resilience of critical infrastructures requires determining the ability of systems to withstand specific threats and return to normal operations after degradation. Thus, comprehensive consideration of all parts of infrastructure systems, from threats to consequences, is needed. The methodology must generate reproducible results that can support decision-making in risk management, disaster response, and business continuity. Argonne National Laboratory, in collaboration with the DHS Protective Security Coordination Division, has developed a comprehensive methodology that uses uniform and consistent data to develop a resilience index (RI). Using the RI to compare similar facilities can provide vital benefits to owners/operators as well as DHS.