Purpose: This research uses the social science perspectives of institutions, ecological modernization and social movements to analyze the rationale used by the early-adopting universities of fossil fuel divestment in the USA. Design/methodology/approach: Through analysis of qualitative data from interviews with key actors at the universities that divested their endowments from fossil fuels, the paper examines how institutions navigate competing logics and frame their rationale. Findings: The results show that while many institutions relied on ecological values embedded in their missions to justify their decision to divest, many also continued to embrace an altered version of market logic. Research limitations/implications: This research is primarily limited by its small population size. If the number of adoptees increases in the future, quantitative analysis should look for statistically robust trends. Practical implications: The implications of this research are that we can expect more universities to commit to divesting from fossil fuels if their mission statements provide them with cultural material to rationalize the decision, but also expect them to couch the decision in continued goals and concerns for fiduciary responsibility and the subsequent growth of their endowment. Social implications: Social actors engaged in the fossil fuel divestment campaign may take this research and conclude that they need to build their arguments around the existing institutional logics and cultural identity. Originality/value: This paper contributes original primary data documenting how institutional actors confront dominant logics using both a mixture of internal cultural identity and the reframing of the legitimated market logics.