SUMMARY
Environmental, social, and governance (ESG) rating agencies, acting as relevant financial market actors, should take a stand on working towards achieving a more sustainable development. In this context, the objective of this paper is, on the one hand, to understand how criteria used by ESG rating agencies in their assessment processes have evolved over the last ten years and, on the other hand, to analyze whether ESG rating agencies are contributing to fostering sustainable development by the inclusion of sustainability principles into their assessment processes and practices according to the ESG criteria. This research is based on a comparative descriptive analysis of the public information provided by the most representative ESG rating and information provider agencies in the financial market in two periods: 2008 and 2018. The findings show that ESG rating agencies have integrated new criteria into their assessment models to measure corporate performance more accurately and robustly in order to respond to new global challenges. However, a deep analysis of the criteria also shows that ESG rating agencies do not fully integrate sustainability principles into the corporate sustainability assessment process.