Critical Infrastructures are systems that are used for the delivery of goods, services or resources that are perceived to be critical. The European Commission has issued its concern about the security of critical infrastructure in Europe, as it is threatened by the potential of failures in those infrastructures that are used in the process of distributing valuable goods and services. The main infrastructure under focus in this paper is the infrastructure used for the delivery and supply of electrical energy. This document describes an assessment that has been carried out on the regional... vulnerability for energy disruption. The chosen approach consists of mix between pure network approaches and pure regional approaches to emphasize the relationship between a region and a European wide network. The used approach starts with exploring the main features of an energy disruption based on both literature study and a modeling exercise. These main features later fit into a description of the network and the region that seeks to determine the most relevant characteristics of regional vulnerability electricity disruptions. This document suggests describing vulnerability of this kind by looking at mission, operation and essential infrastructure. This means that for a system such as the system for the distribution of electrical energy both its use in a region (mission), the organization of the distribution (operation) as well as the necessary infrastructure is considered as elements in assessing vulnerability. The novelty of this research is that it applies knowledge on energy black outs and the cascading of black outs in large scale networks with regional features. By doing so, some of the dynamics of cascading has been capture and brought into the practice of regional vulnerability assessment. The final results have been matched against historic cases of energy outages.