Programs for preventing violence among youth should be evaluated to determine if they are effective. Nurses' logs appear to be a useful tool for evaluating school-based violence prevention programs. The logs provide a record of students' visits to the school nurse that can be used to determine if a violence prevention program is associated with a reduction in fighting- and other injury-related nurse visits. This method has many strengths: it is simple and inexpensive, it does not interrupt the school routine, it permits school-level rather than student-level data collection, it provides a ready "baseline," and it allows continuous data collection. However, potential limitations do exist. For example, the method may provide insufficient information and may be affected by factors unrelated to the intervention. School officials can increase the usefulness of the logs by encouraging standardization and providing training in their use.