The business cycles of countries with greater bilateral trade and multinational production linkages are more closely correlated. But the meaning of this empirical relationship is not well understood. Some contend that these linkages allow for the transmission of shocks across countries, while others argue that countries that trade more with each other are similar in other ways and are thus subject to common shocks. Using data from France, this column examines the properties of international co-movement at the firm level. Even after controlling for common shocks, there is still substantial evidence of transmission of shocks through trade and multinational linkages. Furthermore, trade linkages matter more than multinational ones, especially when it comes to the aggregate impact.