The Federalist party, in U.S. history, is a name that was originally applied to the advocates of ratification of the Constitution of the United States of 1787. Later, however, it came to designate supporters of the presidential administrations of George Washington and John Adams and especially supporters of the fiscal policies of Treasury Secretary Alexander Hamilton.

Until 1795 the Federalists were not a political organization in any modern sense. Rather, Federalism was a frame of mind, a set of attitudes that included belief in a strong and activist central government, public credit, the promotion of commerce and industry, and strict neutrality in the French Revolutionary Wars--all of which were generally reflected in government policy. Opposition arose on all these points, however, and became increasingly organized around James Madison and Thomas Jefferson. Federalists began to adopt the tactics of the opposition Democratic-Republicans in response to attacks on Jay's Treaty with Britain (1794), which Federalists believed preserved neutrality and Democratic-Republicans charged was anti-French. Although parties were widely regarded as inimical to free government, and although Washington, Hamilton, and Adams deplored their rise (together with the tendency toward a North versus South and pro-British versus pro-French polarization of political opinion), parties were an established fact by the presidential election of 1796.

During Adams's presidency the Federalists attempted to stifle dissent by the Alien and Sedition Act (1798). These, however, had the effect of stiffening the opposition at the time when the Federalists themselves were splitting into "High" and "Low" wings over the issue of the XYZ Affair and the ensuing Quasi-War with France. By the election of 1800, therefore, the Democratic-Republicans gained control of the federal government. The death of Washington in 1799 and of Hamilton in 1804 left the Federalists without a powerful leader, and they proved inept at the highly organized popular politics of the Democratic-Republicans. Although the party continued to have strength in New England, expressing the opposition of commercial interests to the Embargo Act of 1807 and the War of 1812 , it never made a comeback on the national level. After the Hartford Convention of 1815, the Federalists were a dying anachronism.