Purpose: This thesis examines the origins and development of Sustainability Reporting in Europe, culminating with the establishment of the European Sustainability Reporting Standards (ESRS) and the Corporate Sustainability Reporting Directive (CSRD). It explores their integration into corporate reporting practices and their potential impact on corporate strategy. This study aims to understand whether mandatory ESG reporting can create an ecosystem for companies to improve their sustainability performance. Design/methodology/approach: The research is conducted within the context of an internship at a Big4 Sustainability Reporting and Assurance department. A qualitative research methodology is employed, integrating immersive observation and participation, systematic document analysis of internal reports, client documentation, academic papers and regulatory texts, and semi-structured interviews with consulting professionals and industry experts to explore their experiences and perceptions.