We study how scheduling demands shape gig-work supply and its composition in an experiment with U.S. gig workers, eliciting reservation wages for contracts varying in advance notice, timing, and duration. No-notice contracts raise reservation wages by 13–14 percent, while outside-hours work with notice carries little penalty. Women require 5–6 percent more than men for outside-hours or no-notice work, and 8–9 percent more when combined. These gaps are largest among workers with heavy household-chore burdens and inflexible schedules. Higher-productivity workers also require larger no-notice premiums. At a given wage, demanding contracts therefore reduce labor supply and select a lower-productivity labor pool.