The author estimates the influence of foreign corporate ownership and international unionism on strike activity in Canadian manufacturing between 1965 and 1985, controlling for several other determinants of strike activity that were largely ignored in previous studies. He finds, contrary to the results of other studies, that the incidence and duration of strikes did not differ significantly between foreign-owned and domestically owned firms or between international and national unions. Strike incidence was significantly lower, however, among unions affiliated with the AFL-CIO than among unions affiliated with a Canadian federation.Few would deny that multinational corporations are of vast importance in today's global economy. Exactly how these corporations affect labor relations in an individual country, however, is not well understood. Moreover, how labor should respond to multinational corporations is a contentious question. Some labor advocates strongly argue that an international response by organized labor-action coordinated across international union locals-is necessary if organized labor is to be an effective representative of workers. Yet, there has been little research on the difference between national unions and international unions, that is, between unions