This book is an absolutely fascinating account of the impact of ethnic diasporas on the U.S.-Canada security relationship. Focusing not only on Muslim-North Americans, but also on Irish-Americans and German-Americans, David Haglund brings in much needed historical perspective to current debates on both sides of the border. As Haglund shows, ethnic diasporas have profoundly shaped the security relationship for 150 years and will no doubt continue to do so in the future. Anyone interested in the intersection of demography and security in general and the U.S.-Canada security relationship in particular should read this book.