Informal workers make up over two billion workers or about 50% of the global workforce, yet, surprisingly, scholars know little about these workers’ political or civil society participation. For decades, researchers argued that informal workers rarely organized or participated in civil society and politics. However, millions of informal workers around the world start and join unions. This raises a related question: Why do informal workers organize in some places more than others? The reality of informal work described in this book and supported by surveys in 60 countries, over 150 interviews with informal workers in Bolivia and Brazil, ethnographic data from multiple cities, and administrative data upends the conventional wisdom on the informal sector. The contrast between scholarly expectations and emerging data underpin the central argument of the book: Informal workers organize where state officials encourage them to.