This article reconsiders one of the most well-known and longstanding arguments in comparative social analysis: S.M. Upset's thesis on the value differences between Canadians and Americans. Beginning with a substantive assessment of Upset's argument, we outline some apparent inconsistencies and related problems in his formulation. We then draw on a range of comparable measures from recent national surveys in both countries and find virtually no empirical support for Lipset's thesis. Most results indicate either no significant national differences or else differences that are opposite to those indicated by Upset's argument. The application of a multiple indicators model, with or without controls on other background variables, fails to alter these results. The article concludes with some speculations on reasons for the lack of support for Upset's thesis in the contemporary period and with some suggestions about the inherent difficulties that are associated with origins explanations.