Diagnostic excellence depends on recognizing the contributions of all team members involved in patient care. This review draws on historical, legal, theoretical, and scientific evidence to examine registered nurses’ diagnostic roles. The authors argue that regulatory barriers, limited visibility in health information systems, and gaps in clinical-reasoning preparation constrained nursing contributions. They call for systematic inclusion of nurses in team-based diagnosis.For more from author Kelly Gleason, PhD, RN, FAAN watch her Editor's Pick Q&A.