Disclosure represents an evergreen topic in banking since it allows breaking down the opacity of the so-called “black box” banks. The recent failures of Silicon Valley Bank and Credit Suisse in March 2023 have reignited discussions about the role played by banking disclosure and its link to transparency, financial stability, and competition. Given these premises, this book comprehensively explains how banking disclosure has evolved in the last decades, shaping banks’ behaviors and mainly investors' decision-making. The book provides an in-depth review of the field, highlighting theories and empirical studies about banking disclosure grounded on regulatory mandates and voluntary initiatives mitigating agency conflicts and addressing information asymmetries. Then, this book discusses banks' need to enhance their disclosure practices to comply with stress tests and contribute to sustainable development, particularly in light of climate change risk. To this end, an empirical investigation uncovers banks scrutinized by regulators and supervisors are more inclined to engage in green lending and prioritize borrowers’ ESG disclosures, thus promoting a more sustainable economy. Lastly, this book presents the state of the art about the link between banking disclosure and sustainability, suggesting potential avenues for future research.