Sixty nursing homes were randomly allocated to receive or not to receive a quality assurance intervention. The experimental intervention included the use of predeveloped quality assurance packages, the services of a quality assurance consultant, and the process of working through the quality assurance cycle with one of two principal indicator conditions. Two prevalent health problems, hazardous mobility and constipation, were selected as the principal indicator conditions. To detect co-intervention, one of two hidden secondary indicator conditions (potential skin breakdown and urinary incontinence) was assessed in each facility. In the control nursing homes, both the principal and secondary indicator conditions were hidden from staff. The care for 1,525 residents was examined before and after the intervention using a retrospective record review initiated for the study purposes. Improvement in management of the principal conditions, hazardous mobility and constipation, was greater in the experimental group (P< 0.03 andP< 0.005, respectively). Neither group changed its management of the hidden conditions. Behavior change was achieved using quality assurance-linked interventions. Further research should focus on refining quality assurance interventions that provide staff education and motivational strategies.