The off-peak work environment is important to understand because the risk for mortality increases for patients at night and on the weekend in hospitals. Because critical-care nurses are on duty in hospitals 24 hours a day, 7 days a week, they are excellent sources of information regarding what happens on a unit during off-peak times. Inadequate nurse staffing on off-peak shifts was described as a major problem by the nurses we interviewed. The study reported here contributes the type of information needed to better understand the organization of nursing units and nurse staffing on outcomes.