Internationalism has long been central to Canadian foreign policy. Although often invoked by governments and individuals, and much debated, it remains an ill-defined, even obscure concept. This article assesses empirically how the Canadian public regards internationalism, and explores the underlying structure of internationalist attitudes. Public opinion data from 1985 provide evidence of four dimensions of attitudes: active, economic, liberal-conservative and independent internationalism. There is a strong consensus on the first two types of internationalism but no such consensus behind the others. Scattered data from across the post-Second World War period seem to support these findings. Using such a typology of internationalism may both illuminate debates on Canadian foreign policy and advance studies of Canadian public attitudes.