A gap analysis was used to examine the scope of school nursing practice in the United States. An investigator-developed 39-item self-assessment survey of scope of school nursing practice was modified from an existing validated tool, organized around the five principles of the National Association of School Nurses' Framework: Standards of Practice, Quality Improvement, Care Coordination, Community/Public Health, and Leadership and also explored barriers to practice. The survey was sent to a national convenience sample of practicing school nurses. The survey was completed by 3,108 practicing school nurses. Gaps were identified for all principles and were greatest for Quality Improvement and Community/Public Health practice. All practice items were rated more important than the ability to practice that item (p < 0.001). Self-identified barriers including workload, school/district expectations, and state regulations accounted for significant variances in practice across four of five principles (p < 0.05, p < 0.001). Recommendations include support for population-focused evidence-based school nursing practice.