Every ten years it is decline time in the United States. The declinist vision is so recurrent that it seems a constant countermelody of American exceptionalism. The paper offers an appraisal of the recent American debate on U.S. decline. The first section shows the persistence of the debate, pointing out what has changed in the decline perceptions after the end of the Cold War. The second section presents a brief summary of main arguments claiming the instability or the stability of unipolarism, respectively predicting the decline and the steadiness of American hegemony. Finally, the paper focuses on the open-ended character of the debate, its inconclusiveness and its shortcomings.