The Crittenden Compromise (December 18, 1860) was an unsuccessful proposal by Kentucky Senator John J. Crittenden to resolve the U.S. secession crisis of 1860–1861 by addressing the concerns that led the states in the Lower South of the United States to contemplate secession. It consisted of a preamble, six proposed constitutional amendments, and four proposed Congressional resolutions. Both the House of Representatives and the Senate rejected it in 1861. It was widely perceived as making heavy concessions to the South, but perhaps the most significant aspect of it was Abraham Lincoln's immediate rejection and the South's reaction to his rejection that paved the way for further bloodshed in the Civil War.

There were many unpopular features of the Compromise that led to its failure. It guaranteed the permanent existence of slavery in the slave states and addressed Southern demands in regard to fugitive slaves and slavery in the District of Columbia. But the heart of the Compromise was the permenant reestablishment of the Missouri Compromise line: slavery would be prohibited north of the 36° 30’ parallel and guaranteed south of it. The Compromise further included a clause that it could not be repealed or amended.

The Compromise was popular among Southern delegates in the Senate, but it was impermissible to the Republicans (free soilers at this time) who believed that slavery must not be allowed to expand. This led to Lincoln's condemnation of the Compromise as one that did not deal with the future of slavery in America. He declared that were the Compromise accepted, it "would amount to a perpetual covenant of war against every people, tribe, and state owning a foot of land between here and Tierra del Fuego."