This article contributes to the emerging stream of micro-institutional research, which zooms in on the internal organizational processes that are responsible for organizations' differential responses to the external environment. Specifically, the investigation offers new knowledge of how organizational identity processes can shape whether decision makers will resist versus give in to environmental pressures. Building on the notion that organizational identity acts as a filter through which decision makers relate to the external environment, I develop the theoretical argument that strong organizational identification increases resistance to environmental pressures due to two mechanisms: (1) it bolsters the decision maker's certainty and (2) it deflects the decision maker's attention from the environment. A series of laboratory experiments not only test the mediated relationship between organizational identification and resistance to environmental pressures but also contrasts different types of organizational identity. The empirical results support the hypothesized positive link between organizational identification and resistance, which becomes particularly strong when the organizational identity is normative (vs. utilitarian). The findings reported here enrich institutional theory by adding microfoundations to organizational practice-adoption decisions and shedding new light on relevant enabling conditions for agency and within-field heterogeneity.