Sustainability reporting helps companies disclose information about its activities and such strategies. Furthermore, it allows them to manage change to make their operations more sustainable. Through sustainability reporting, stakeholders become well informed of the businesses they are investing in and be assured that companies do integrate sustainable practices into their operations. It is with these benefits in mind that the ASEAN CSR Network (ACN), in collaboration with Centre for Governance, Institutions and Organisations (CGIO) at NUS Business School, conducted a study on four countries in the Association of Southeast Asian Nations (ASEAN), to find out the state of sustainability reporting in these countries. Countries included in the study are Indonesia, Malaysia, Singapore and Thailand. The development and extent of reporting in each country is studied and the state of overall progress of reporting in ASEAN is analysed.