In Stand on Guard, Stephanie Carvin sets out to explain the range of activities considered national security threats by Canadian security services today. As new forms of terrorism and extremism appear, especially online, we need a responsibly widened view of such threats and how they manifest in the contemporary world. Canadians should not be more fearful, Carvin explains, but a more sophisticated understanding among security services personnel and the general public is needed if we are to anticipate and ameliorate threats to national security. As a former security analyst tasked with providing threat assessments to high levels of government, Carvin writes with both authority and urgency. Her book presents an insider’s look at the issues facing the Canadian security and intelligence community. Timely and accessible, Stand on Guard will be required reading for scholars, practitioners, and any Canadian concerned about national security in the twenty-first century.