School nurses represent an important resource for addressing pediatric obesity and weight-related health. However, school nurses perceive numerous barriers that prevent them from addressing the weight-related health of students. The current study developed and tested a new, comprehensive measure of nurses' perceptions of 10 types of barriers to addressing pediatric weight in a nationally representative sample of 214 school nurses. The measure was developed in the context of Bronfenbrenner's (1979) ecological systems theory and includes subscales assessing nurses' perceptions of skills-based, job-related, and societal barriers. Confirmatory factor analyses (CFAs) provided evidence for the validity of the measure, including the three barrier subscales. In addition, the subscales demonstrated adequate internal consistencies. Results indicate that school nurses perceive barriers to addressing weight-related health on multiple ecological levels, which may inform intervention or continuing education efforts. Future pediatric weight programs that involve school nurses might consider using the measure to assess nurses' perceptions of barriers. (Contains 2 tables.)