This chapter focuses on the main criticality methodologies developed for the assessment of critical and strategic metals. It contains an overview of the most important abiotic depletion indicators used in Life Cycle Assessment and their main shortcomings, which have led to the development of new methodologies, such as criticality. The chapter follows the historical evolution of the criticality methodologies, starting with the first study published by the United States National Research Council and continuing with the Criticality Assessment of the European Commission and the framework developed by Graedel and his team at Yale. The chapter contains information about the evaluation process and the indicators used in each of these methodologies and discusses the updated list of critical materials published in 2017 by the European Commission. It closes with an overview of current research performed in this field, namely the extension of the methodology to other resources, like water and gravel, and the consideration of the dynamic character of the indicators.