In this lesson, students will identify multiple economic, social, and geopolitical factors that influenced Americans’ attitudes about the United States’ role in the world from 1939–1941, when people in the United States were deeply divided about what actions, if any, America should take in defense of countries threatened by German military conquest. Through an examination of primary source documents, students will identify and evaluate arguments that different Americans made for the provision of military materiel to Britain in 1940. Ultimately, students will reflect on questions that this lesson raises about America’s role in the world today.