The Naturalization Act of 1798 (, enacted June 18, 1798) was a law passed by the United States Congress, to amend the residency and notice periods of the previous Naturalization Act of 1795. It increased the period necessary for aliens to become naturalized citizens in the United States from 5 to 14 years and the Declaration of Intention from 3 to 5 years.
Although the law was passed under the guise of protecting national security, most historians conclude it was really intended to decrease the number of citizens, and thus voters, who disagreed with the Federalist Party. At the time, most immigrants supported Thomas Jefferson and the Democratic-Republicans, the political rivals of the Federalists. It had only limited effect, however, as many immigrants rushed to become naturalized before the Act went into effect, and states could at the time make their own more lenient naturalization laws.
The Act was controversial at the time, even within the Federalist Party, as many Federalists feared it would discourage immigration.