Schools play a key role in promoting public health. Yet, these initiatives also face opposition from parents, and such opposition may be increasing in the wake of misinformation campaigns and efforts to politicize public health. During the COVID-19 pandemic, for example, parent opposition helped derail schools’ efforts to require masks and vaccines. Thus, it is important for educators and policymakers to understand the extent, source, and nature of parents’ opposition to new school-based public health initiatives. Combining data from a national survey of US parents (N=1,945) with a content analysis of a Facebook group for parents in one politically divided school community, we found that, at the peak of the pandemic (December 2020), nearly one third of parents opposed each of our two focal initiatives. We also found that parents based their opposition to (or support for) school-based public health initiatives on individualistic calculations about the costs and benefits those initiatives would impose on their individual child. Those calculations, however, did not always follow the same logic. In light of those varied logics, vaccine opposition was most common among Republicans, mothers (especially white mothers), parents without college degrees, and Black parents. Meanwhile, opposition to mask mandates was disproportionately common among Republicans, fathers, and college-educated parents (especially among white parents), as well as among those who had COVID-19. We conclude that individualistic approaches to parental decision-making are preventing communities from enacting and maintaining school-based public health initiatives and undermining health and education as public goods.