Many companies in different industrial sectors are exploring alternative work schedules to deal with diverse problems associated with shiftwork. The use of extended workday schedules (regular shift lengths exceeding 8 h with compressed workweeks) is attracting growing interest in many industries that use continuous operations. To address concerns regarding possible fatigue effects on safety and work performance associated with such schedules, the U.S. Bureau of Mines conducted a two-phase study at an underground metal mine in western Canada. Data were collected before and after a group of workers employed at the mine changed from an 8- to a 12-h schedule. Results indicate nearly unanimous acceptance and improved sleep quality associated with the new schedule. In general, fatigue-sensitive behavioral and physiological performance measures show either no change or improvement with 12-h shifts. We conclude that the extended workday schedule should be retained but periodically reevaluated.