The study aimed to investigate the relationship between sustainability disclosure and accounting conservatism. It also examined the impact of ownership concentration and industry type on this relationship. The study relied on the most recent sustainability framework issued by the Egyptian Financial Supervisory Authority in 2021 as a basis for measuring the level of sustainability reporting disclosure. Published sustainability reports (in the annual reports or standalone sustainability reports) for a sample of (105) non-financial joint-stock companies during the period (2022-2024) were reviewed and analysed using content analysis to test the study hypotheses. Based on theories explaining sustainability disclosure, the study controlled for the effects of (company size, leverage, degree of company complexity, earnings volatility, company age, and audit quality) on the dependent variable. The study found a significant positive effect of the level of disclosure of (environmental performance, social performance, and sustainability governance performance ) on accounting conservatism. The study results also found that ownership concentration has a moderating effect on the relationship between the level of disclosure of environmental performance and sustainability governance performance and accounting conservatism. It interacts with environmental performance disclosure to have a positive effect on accounting conservatism, and with sustainability governance performance to have an inverse effect on accounting conservatism. The results also showed a moderating effect of industry type on the relationship between the level of disclosure of environmental performance, social performance, and sustainability governance performance and accounting conservatism. Industry type interacts with the level of disclosure of environmental performance and social performance to have an inverse effect on accounting conservatism, and with sustainability governance performance to have a positive effect on accounting conservatism. Based on this, the study recommends that companies be directed to enhance sustainability disclosure. It also recommends that investors and financial analysts be aware of the importance of corporate sustainability disclosure, given its impact on financial analysts' assessments. Overall, this study contributes to the existing literature on the relationship between sustainable performance and financial reporting quality. The findings provide practical implications for companies adopting conservative accounting practices in response to social and environmental responsibility disclosure initiatives in the form of sustainability reports. Keywords: Sustainability Reporting, Accounting Conservatism, Ownership Concentration, Industry Type.