Pundits have often claimed, but scholars have never found, that swings in par-tisan sentiment abroad predict electoral fortunes at home. Employing semi-annual Eurobarometer survey data on vote intent in eight European countries between 1976 and 1997, I provide the first statistical evidence for such interna-tional partisan waves and find evidence of causation in international business cycles. An error correction model associates a ten percentage point change in support for the left among a country's neighbors with a 4.3 point change at home over the long-run. Short-run effects, however, have increased both over time and with trade openness, suggesting a role for international economic in-tegration. Synchronous unemployment shocks among economically integrated European states explain at least some of the international comovment in vot-ers' partisan preferences. Globalization, in contrast to the assumption of most comparative electoral research, has a substantial effect on domestic politics.