Historically, teachers unions have played a special role in strengthening democratic cultures, and they are urgently called on to do so again. What is needed now more than ever says Kahlenberg, is a "social justice unionism" that goes beyond the narrow self-interest of members in bargaining for better wages and benefits to also engage in critical fights for public schooling, trade unionism, and civil rights at home and abroad. In this article the author argues that this movement needs to not only fiercely resist bad ideas but also offer a new, vibrant, inclusive vision that can be a model for people who champion democratic values across the globe.