Canada agreed in March 1948 to join the United Kingdom and United States in discussions that led, eventually, to the creation of the North Atlantic Treaty. Canada's action was, in some ways, unprecedented. Despite fighting in the First and Second World Wars at the side of Britain, Canada had never made a formal commitment to Imperial defence. Outside of those wars, Canada had never even made a real contribution to her own defence. Why, then, did Canada assume a prominent role in the creation of the Treaty? The answer may be found in an analysis of the formulation of Canadian policy and the considerations upon which it was based: domestic politics, economics, defence, and internationalist ideals.