Interdependencies among critical infrastructure systems are well-recognized as key points of vulnerability that can compromise system performance especially during extreme events. At the heart of these vulnerabilities are decisions, often unnoticed and indirect, which occur anywhere from infrastructure planning, siting and design through operation and maintenance. The key contributions of the paper are (i) the presentation of a method for constructing a catalog of infrastructure inter dependencies, (ii) the construction of a set of indicators transferable to other databases, and (iii) preliminary analytical results of the application of the indicators to a sample database of catalogued events with interdependencies. This paper addresses how case analysis findings can be used in decision making to promote non-adverse interdependency-related outcomes from extreme events. Critical infrastructure analyzed includes facilities and services for transportation, telecommunications, water supply, wastewater, electric power and other energy infrastructure. Event databases for this research include government, industry, academic and media reports.