The Foundations of the Nineteenth Century (Die Grundlagen des neunzehnten Jahrhunderts, 1899) is a book by British-born Germanophile Houston Stewart Chamberlain. In the book, Chamberlain advances various racist and especially völkisch antisemitic theories on how he saw the Aryan race as superior to others, and the Teutonic peoples as a positive force in European civilization and the Jews as a negative one. It was his best-selling book.

Originally published in German, the book focuses on the controversial notion that Western civilization is deeply marked by the influence of the Teutonic peoples. Chamberlain grouped all European peoples—not just Germans, but Celts, Slavs, Greeks, and Latins—into the Aryan race”