Think Tank Transparency Act This bill requires certain nonprofit organizations to file a disclosure report with the Department of Justice (DOJ) after (1) receiving a gift, donation, or contribution of $10,000 or more in a calendar year from foreign governments, entities, or individuals; or (2) entering into or modifying a contract or agreement with such foreign sources. These disclosure reports shall be available to the public on the DOJ website. Generally, these requirements shall apply to certain nonprofit organizations that (1) seek to influence U.S. public policy or public opinion; (2) engage in or publish substantial policy-related research or scholarship; or (3) regularly promote events featuring reporters, journalists, or government officials. Furthermore, if such a nonprofit organization presents research (e.g., briefings or testimony) that was funded by a foreign source to Members of Congress, congressional employees, or executive branch officials, that foreign source must be prominently identified on any presented written materials. The bill permits the DOJ to bring a civil action against an organization to compel compliance.