The Dunning School was an historiographical school of thought regarding the Reconstruction period of American history (1865–1877), supporting conservative elements against the Radical Republicans who introduced civil rights in the South. It was named for Columbia University professor William Archibald Dunning, who taught many of its followers.

The Dunning School viewpoint favored conservative elements in the South (the Redeemers, plantation owners and former Confederates) and disparaged Radical Republicans who favored civil rights for former slaves. The views of the Dunning School dominated scholarly and popular depictions of the era from about 1900 to the 1930s. Adam Fairclough, a British historian whose expertise includes Reconstruction, summarized the Dunningite themes:

All agreed that black suffrage had been a political blunder and that the Republican state governments in the South that rested upon black votes had been corrupt, extravagant, unrepresentative, and oppressive. The sympathies of the "Dunningite" historians lay with the white Southerners who resisted Congressional Reconstruction: whites who, organizing under the banner of the Conservative or Democratic Party, used legal opposition and extralegal violence to oust the Republicans from state power. Although "Dunningite" historians did not necessarily endorse those extralegal methods, they did tend to palliate them. From start to finish, they argued, Congressional Reconstruction—often dubbed "Radical Reconstruction"—lacked political wisdom and legitimacy.

Historian Eric Foner, a leading specialist in the Reconstruction Era, said of the Dunning School academics:

The traditional or Dunning School of Reconstruction was not just an interpretation of history. It was part of the edifice of the Jim Crow System. It was an explanation for and justification of taking the right to vote away from black people on the grounds that they completely abused it during Reconstruction. It was a justification for the white South resisting outside efforts in changing race relations because of the worry of having another Reconstruction. All of the alleged horrors of Reconstruction helped to freeze the minds of the white South in resistance to any change whatsoever. And it was only after the Civil Rights revolution swept away the racist underpinnings of that old view—i.e., that black people are incapable of taking part in American democracy—that you could get a new view of Reconstruction widely accepted. For a long time it was an intellectual straitjacket for much of the white South, and historians have a lot to answer for in helping to propagate a racist system in this country.

In contrast to Foner's views, Fairclough argued that the influence of the Dunning School outside of academia was minimal; its hostile view of Reconstruction had already been established as the predominant view in white society long before any of the Dunning School historians published their works on Reconstruction. Works of popular culture like The Birth of a Nation that shared its view of Reconstruction did not use its historians as a source.

The school was named after Columbia University professor William Archibald Dunning (1857–1922), whose writings and those of his Ph.D. students comprised the main elements of the school. He supported the idea that the South had been hurt by Reconstruction and that American values had been trampled by the use of the U.S. Army to control state politics. He contended that freedmen had proved incapable of self-government and thus had made segregation necessary. Dunning believed that allowing blacks to vote and hold office had been "a serious error". As a professor, he taught generations of scholars, many of whom expanded his views of the evils of Reconstruction. The Dunning School and similar historians dominated the version of Reconstruction-era history in textbooks into the 1960s. Their generalized adoption of deprecatory terms such as scalawags for southern white Republicans and carpetbaggers for northerners who worked and settled in the South, have persisted in historical works.

Explaining the success of the Dunning School, historian Peter Novick noted two forces — the need to reconcile the North and the South after the Civil War, and the increase in racism as Social Darwinism appeared to back the concept with science — that contributed to a "racist historiographical consensus" around the turn of the 20th century on the "criminal outrages" of Reconstruction. Novick provided examples of the style of the Dunning School approach when he wrote: