The premise underlying the proposed intervention study is that errors in prescribing and monitoring warfarin for nursing home residents are related to problems in the system of care. The system of medication management in the nursing home includes the nursing staff within the facility, and the physicians, laboratories, and pharmacy vendors generally external to the nursing home who interact to provide services to the residents. While an adverse drug event in this setting may be directly linked to a "human error", the root cause may be defined as the defect in the system that permitted such an error to occur. In the case of warfarin therapy management for nursing home residents, an important root cause is poor information flow. One example is a telephone call to a covering physician about a resident with a urinary tract infection without providing crucial information that the resident is taking warfarin. The result may be an order for an antibiotic that interacts with warfarin, leading to an increased risk of a bleeding complication.