Schools and school districts are key to U.S. vaccination policies: They communicate immunization enrollment requirements and enforce them during registration. This article presents a mixed-methods study of how Michigan's 537 districts communicate about vaccine mandates through public-facing websites. It reports the results of a qualitative analysis (n = 50) of websites from Southeast Michigan and a quantitative analysis of all (n = 537) Michigan's district websites. School district websites engage in diverse health promotion practices surrounding immunization, from encouraging vaccination to neutral messaging and to encouraging exemptions. Most provide scant immunization information and few promote the importance of immunization for individual and community health. We recommend that school nurses, district staff, and health authorities collaborate to ensure that school district communication promotes immunization and does not promote nonmedical exemptions. This can lead schools to embrace immunization as an essential activity for their own functioning rather than as an unwelcome requirement imposed by outside agents.