Discoverability means users can “discover” selected values (e.g., who, what, where, when), but cannot gain access to the underlying information until the user requesting access is authorized and authenticated. This brief defines the potential results of employing discoverability in the government’s information sharing system. The Markle Task Force identifies discoverability as the first step of an effective system for information sharing and urges the Obama Administration and Congress to consider this concept in national security policy-making.