The Russian government has claimed that the Western powers promised at the end of the Cold War not to expand NATO, but later reneged on that promise. Most former officials in the West, and many scholars as well, have denied that this was the case; but other scholars, along with a handful of former officials, believe that promises to that effect were, in fact, made in 1990. So who is right? The question still has political importance: how it is answered has bearing on how we should feel about NATO expansion and, indeed, about the United States' post–Cold War policy more generally. So it makes sense to stand back and try to see where the truth lies. An examination of the debate in light of the evidence—especially evidence that the participants themselves have presented—leads to the conclusion that the Russian allegations are by no means baseless, which affects how the U.S.-Russian relationship today is to be understood.