For more than 30 years, a negative "off-peak effect" on patient outcomes has been associated with weekend and/or nighttime hospitalization in more than 25 diagnostic groups. Descriptive studies have verified the presence of this off-peak effect on patient outcomes but have done little to explain its cause. Institutional ethnography is a promising method for describing challenges nurses encounter and deal with on off-peak shifts and for exploring how those challenges arose in institutions designed to avoid such outcomes. The authors discuss their research and suggest a number of steps that nurse administrators might take to enhance their knowledge for handling off-peak challenges in their hospitals.