This dissertation examines the origins, functions, and effects of precarious schedules—characterized by unpredictable timing or hours of work—in the US labor market. I focus on the retail sector, which has drawn scrutiny for unstable scheduling practices, such as on-call shifts and variable part-time hours, that compound more familiar problems of low wages and inadequate benefits for retail workers. My dissertation advances sociological understanding of this topic by theorizing schedules as risk governance arrangements, reconceptualizing precarity in terms of frustrated expectations, and conducting novel analyses of the causal effects of specific types of schedules. I evaluate the thesis that unstable scheduling provides advantages for employers in the short term, but can be counterproductive in the longer term by undermining commitment and skill formation in the employment relationship.I develop a model of work as an option that formalizes and refines the notion of risk shifting from employers to workers through unstable scheduling. Unlike a secular process of externalizing risks, unstable schedules function as a call option, allowing employers to realize potential gains while avoiding anticipated losses to transacting for available labor. This contingent and asymmetric arrangement gives employers flexibility but precludes mutual commitment to a consistent schedule. I argue that commitment and consistency promote the formation of human and social capital that can improve performance and well-being at work. I conceive of the trade-off between optionality and commitment in the scheduling process as a reflection of the dual character of labor as a cost of production and a productive asset. The dissertation comprises three empirical studies. The first study analyzes data from the National Longitudinal Survey of Youth 1997 Cohort to identify compensation penalties for unpredictable and unstable schedules. The second study traces the emergence of a precarious retail labor force through historical documents, statistics, and secondary research spanning 1900–2019. The third study exploits a field experiment and high-frequency administrative data from the Stable Scheduling Study to analyze the relationship between consistency and labor productivity in twenty-eight clothing stores. I find mixed results that nonetheless shed light on the governance of risk in the scheduling process. Workers with precarious schedules generally fare worse in the labor market than otherwise comparable workers with more stable schedules. But modest changes in scheduling stability among treatment stores did not significantly affect store performance as measured by quarterly sales per labor hour.