The Second Party System is a term of periodization used by historians and political scientists to name the political party system existing in the United States from about 1828 to 1854, after the First Party System. The system was characterized by rapidly rising levels of voter interest beginning in 1828, as demonstrated by Election Day turnout, rallies, partisan newspapers, and a high degree of personal loyalty to party.

The major parties were the Democratic Party, led by Andrew Jackson, and the Whig Party, assembled by Henry Clay from the National Republicans and other opponents of Jackson. Minor parties included the Anti-Masonic Party, which was an important innovator from 1827 to 1834; the abolitionist Liberty Party in 1840; and the anti-slavery Free Soil Party in 1848 and 1852. The Second Party System reflected and shaped the political, social, economic and cultural currents of the Jacksonian Era, until succeeded by the Third Party System.