At the heart of Carl Dahlhaus’s historiographic interests, according to James Hepokoski, was an “effort to keep the Austro-German canon from Beethoven to Schoenberg free from aggressively sociopolitical interpretations.” But Dahlhaus did not stop at Schoenberg: he also wrote about postwar music, and one might therefore wonder whether his “Austro-German canon” of autonomous music extended past 1945. In his essays on this period, Dahlhaus claimed that the postwar musical avant-garde was defined by the concept of the experiment, a concept that was, he believed, “nothing less than the fundamental aesthetic paradigm of serial and post-serial music.” He maintained this view from the 1960s through the 1980s, and thereby placed the concept of the experiment at the center of his historiography of postwar music. My paper shows that the concept of the experiment, as defined by Dahlhaus, has a uniquely German pedigree, one that is not at odds with his wider historiographic interests. By making the concept of the experiment central to his account of postwar music, Dahlhaus was thereby able to extend his historiography beyond the canon that ran from Beethoven to Schoenberg and include also later composers. In so doing, he lent the supposedly “international” postwar avant-garde a character that seems specifically German.