American policymakers have long focused on work as a key means to improve economic wellbeing. Yet, work has become increasingly precarious and polarized. This precarity is manifest in low wages, but also in unstable and unpredictable work schedules that often vary significantly week-to-week with little advance notice. We draw on new survey data from The Shift Project on 37,263 hourly retail and food service workers in the United States. We assess the association between routine unpredictability in work schedules and household material hardship. Using both cross-sectional models and panel models, we find that workers who receive shorter advanced notice, those who work on-call, those who experience last minute shift cancellation and timing changes, and those with more volatile work hours are more likely to experience hunger, residential, medical, and utility hardships as well as more overall hardship. Just-in-time work schedules afford employers a great deal of flexibility, but at a heavy cost to workers' economic security.