The Institute of Medicine recommends school-based body mass index (BMI) screening as an obesity prevention strategy. While school nurses have provided height/weight screening for years, little has been published describing measurement reliability or process. This study evaluated the reliability of height/weight measures collected by school nurses and the privacy of the measurement process. Interrater reliability for height/weight measures was computed on 70 elementary students, comparing measurements collected by a trained researcher to those collected by 7 school nurses. Students arrived in small groups to private measurement spaces. Height agreement was 80% for younger and 85% for older students. Agreement for weight was 97% and 100%, respectively. Reliability for weight was very good. Reliability for height was good, but results suggest careful attention to the collection process is required. Nurses may benefit from regular training on measurement procedures. The results of this study suggest that school nurses provide BMI screening that is private and reliable. (Contains 1 table.)