With the growing rate and intensity of disasters, traditional infrastructure design methods have become inadequate for ensuring the resilience of modern infrastructures. To tackle this challenge, researchers have advocated for the adoption of resilience-based design approaches. Within this framework, various approaches have been proposed to assess the resilience of different types of infrastructures. However, these approaches vary in their effectiveness and suitability depending on the specific infrastructure under assessment, the extent of the assessment, and the objectives of the evaluation. This chapter aims to provide clarity and enhance the reader's understanding of the resilience assessment process by presenting the main approaches used in quantifying infrastructure resilience. It outlines the strengths and limitations of each approach, enabling practitioners and researchers to make informed decisions when selecting an appropriate method for assessing infrastructure resilience. By offering insights into the strengths and limitations of these approaches, this chapter facilitates the identification of suitable assessment strategies that align with the specific characteristics and goals of the infrastructure being evaluated. Ultimately, a comprehensive understanding of these assessment approaches is crucial for promoting effective infrastructure design and development practices that enhance resilience in the face of evolving challenges and uncertainties.