If It Had Happened Otherwise is a 1931 collection of essays edited by J. C. Squire and published by Longmans, Green.

Each essay in the collection could be considered alternate history or counterfactual history, a few written by leading historians of the period and one by Winston Churchill.

The original edition included the following essays:[1] A revised edition with the alternate title If: or, History Rewritten was also released by the American Viking Press in 1931, deleting the General Strike essay and adding one new essay along with reprints of two older but previously uncollected ones: Among many other works of alternate-history science fiction: