The text explores the implementation of the European Sustainability Reporting Standards (ESRS) within the specific context of Cooperative Credit Banks (CCBs). The study analyzes the mandatory EU directives the transition from the Non-Financial Reporting Directive (NFRD) to the Corporate Sustainability Reporting Directive (CSRD). Both EU Directives share a sustainability mandatory approach, but CSRD introduce more standardization through the use of the European Sustainability Reporting Standards (ESRS) to disclose sustainability, so promoting the "one-size-fits-all" approach. Through a qualitative case study of ICCREA, the largest cooperative banking group in Italy, the research provided  evidence that sustainability mandatory reporting has evolved. Between 2017 and 2022, ICCREA transitioned toward a double materiality approach, involving stakeholders in identifying the environmental and social impacts of the bank’s operations. Despite this progress, the study finds that general sustainability standards remain inadequate for fully articulating the value generated by the cooperative model. Historically, CCBs have utilized sector-specific frameworks, such as those provided by Federcasse in Italy, which include mutualistic metrics designed to quantify their social impact  and to address the unique CCBs’ stakeholders’ needs, ICCREA has integrated specific mutual indicators into its reporting to better serve the information needs of its stakeholders. The book suggests that the current focus on standardization of sustainability disclosure risks marginalizing the strategic nuances of hybrid organizations like CCBs, and universal frameworks like the ESRS fail to capture these essential characteristics, leading to a reporting gap. For sustainability reporting to remain credible and relevant for CCBs, it must incorporate secondary-level, sector-specific standards that respect and reflect their cooperative identity and social purpose.