Abstract
A recent flurry of labor movement activity has been driven by younger workers, tight labor markets, and a sympathetic federal government. Nonetheless, US union density remains low, even as unions remain popular. This is because employer opposition and US labor law together imply that workers need to overcome substantial collective action problems at work in order to win union recognition and collective bargaining agreements. These barriers make dense social networks and high levels of social capital at work a prerequisite for unionization. Labor organizing can build this social capital, but faces an uphill battle without policy changes that extend collective bargaining across employers and up the value-chain and make unionization easier. Partnering with labor unions, researchers can study theoretical problems of collective action while also getting a window into what strategies of a renewed labor movement may work.