The Republican Party was founded in 1854 to oppose slavery and its spread to new territories and states. Today, under the sway of Donald Trump, it is hardly recognizable as the party of Lincoln or even the party of Eisenhower. How and why has the Republican Party changed so drastically? Kenneth Janda sheds new light on the Republican Party’s transformations, drawing on a wide range of quantitative and qualitative evidence. He examines nearly three thousand planks from every Republican platform since 1856 as well as candidate statements and historical sources, tracing the evolution of the party’s positions on topics such as states’ rights, trade, taxation, regulation, law and order, immigration, environmental protection, and voting rights. Janda argues that the GOP has gone through three main phases over the course of its history, transforming from a party committed to governance to one vehemently opposed to government. In its first several decades, the Republican Party emphasized national authority and economic development. By the late 1920s, Republicans had begun downplaying the role of government in favor of a new philosophy steeped in free markets. The nomination of Barry Goldwater in 1964 marked a key turning point. Since then, the party has endorsed states’ rights, opposed civil rights, and become increasingly ethnocentric. Richly documented with scores of figures and tables, The Republican Evolution offers new perspective on how the GOP became an antigovernment party—and whether it can step back from the brink of authoritarianism.