Abstract Research into disruptions to, or failures in, the Critical Infrastructure (further only CI), represents an important area of investigations into the phenomena in (a) Critical Infrastructure System (further only CIS). The results arising from the prediction of the intensity of problems - and the line(s) of their impacts spread–patterns, are an important part of any decision-making process carried out by the involved parties for the early and effective realization of Safety and Security Measures. Therefore, this article's aim is to assess cascading effects in a CI system. The first part of the article deals with the typology of impacts - the aspects that form their nature; and the ways these impacts spread in a CI structure. Furthermore, the current approaches to the assessment of such cascading impacts are also described. Based on these facts, the authors define the principles and framework for assessing cascading impacts in a CI system. The CIA Method (Cascading Impact Assessment - further only CIA), which serves for the quantification of the spread of cascading impacts in a CIS, is the most important part of this article. The essence of this method lies in its assessment of all lines of business occurring in the chosen area, as well as an assessment of their resilience and links; subsequent to this, a structural map of the risk of the spread of cascading impacts was created.