Handwashing practices are persistently suboptimal among healthcare professionals and are also stubbornly resistant to change. The purpose of this quasi-experimental intervention trial was to assess the impact of an intervention to change organizational culture on frequency of staff handwashing (as measured by counting devices inserted into soap dispensers on four critical care units) and nosocomial infections associated with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). All staff in one of two hospitals in the mid-Atlantic region received an intervention with multiple components designed to change organizational culture; the second hospital served as a comparison. Over a period of 8 months, 860,567 soap dispensings were recorded, with significant improvements in the study hospital after 6 months of follow-up. Rates of MRSA were not significantly different between the two hospitals, but rates of VRE were significantly reduced in the intervention hospital during implementation.