The story of Canada in the North Atlantic Treaty Organization (NATO) is one of consistent support and involvement but of varying levels of military and diplomatic engagement. Canada in NATO, 1949–2019 provides the first analysis of Canada’s involvement in the Atlantic Alliance – from the negotiations leading to the alliance’s charter in 1949 to NATO’s seventieth anniversary – exploring how the country’s role in NATO has evolved over the years. As one of NATO’s early, foremost participants, Canada was a major force contributor in the 1950s. Briefly deploying more modern fighter aircrafts in Europe than the United States had, as well as a naval commitment that would have been responsible for 10 per cent of ship escorts across the North Atlantic, Canada became the “odd man out” of the western alliance as the Cold War wore on due to its spotty military contributions. Yet Canada eventually re-emerged as a significant member through its contributions to NATO peace enforcement operations in the Balkans in the 1990s and its heavy contributions to operations in Afghanistan in the early twenty-first century, finding itself in the unfamiliar position of criticizing many of the allies by which it had for so long been criticized. As the lead nation for the alliance’s “enhanced forward presence” in Latvia, Canada still plays an important and highly visible role in NATO’s efforts in Eastern Europe today. Canada in NATO, 1949–2019 sheds light on how NATO profoundly shaped Canadian defence and foreign policy, while also serving vital Canadian security and diplomatic interests.