School nurses are expected to advocate for policies and procedures that support student health, safety, and school attendance. An educational activity to improve school nurse advocacy was developed and implemented based on advocacy literature, self-efficacy theory, and continuing education guidelines. A quantitative, repeated measure descriptive project design was used to compare school nurses' advocacy measures before and following an educational activity and 6 weeks after the activity. Immediately after the education, there were significant increases in advocacy knowledge (p < 0.001), confidence (p < 0.001), and recalled behaviors (p < 0.01) for a convenient sample of 51 Massachusetts school nurses. There were no significant differences across pre-, post-, and 6-week survey responses (n = 6); however, advocacy outcomes from immediately after the education were maintained at 6 weeks. More effective school nurse advocacy may improve youth population health, increase safety for students at school, and improve school attendance.