Despite the importance of trustees for higher education institutions, few studies address how they influence the institutions they steward. To address this gap, we used a social network approach within a comparative case study design to evaluate how trustees interacted with two private, elite universities: Harvard University and the Massachusetts Institute of Technology. While trustees interacted with these institutions in differing ways, results indicated that some of them significantly influenced institutional behaviors, structures, and policies. This suggests that the role of trustees should be re-conceptualized to reflect their ability to influence higher education institutions, making them a fundamental part of the microfoundations of these institutions.