Although informality is typically associated with developing countries, this article argues that informal activities are an integral part of U.S. cities and should be addressed in planning curricula. It focuses on planning education and suggests a possible course, which includes a seminar covering academic literature on informality in both developing and developed countries, and fieldwork-based, case study research by students. It also suggests that the course can be an important avenue for students to understand inequality and poverty and an excellent method for preparing them to think about institutions and regulations in complex and sophisticated ways.