Worker mobility—the ability to find and take another job—is at the core of worker power, and, conversely, worker immobility is at the core of employer power. This paper presents evidence of barriers to worker mobility in terms of labor market constraints (can a worker find another job?) and financial constraints (can a worker afford to transition to another job?). The theoretical context of these findings is dynamic monopsony: the harder it is for a worker to leave, the more power an employer has over that worker’s wages.