Online disclosures can play a key role in informing consumer decisions. However, cognitive limitations such as information overload, as well as technical ones such as small screen sizes on mobile devices, may limit their effectiveness. Additionally, businesses may sometimes focus on technical compliance with disclosure requirements rather than maximising their effectiveness in informing consumer decisions. This report supports consumer authorities in enhancing disclosure effectiveness by providing i) a systematic overview of key disclosure characteristics; ii) guidance on the effective design of disclosures based on a review of the empirical literature; iii) an overview of overarching challenges to disclosure effectiveness and iv) an overview of possible ways to address them, including possible policy alternatives when disclosures may not be sufficient on their own.