How do social movements affect decisions within corporations, such as the commercialization of new technologies? We suggest that the effect of movement activism is conditioned by the internal polity and therefore varies across organizations. This article examines how the anti-genetic movement in Germany during the 1980s affected six domestic pharmaceutical firms’ commercialization of biotechnology. We develop a process model of how movements penetrate the relatively closed polity of private organizations. External contestation weakened the position of internal champions of biotechnology, precipitated divisions among organizational elites, and undermined collective commitment to the technology. The movement also increased perceptions of investment uncertainty, but the consequences of this uncertainty depended on organizational logics of decision making. As a result, investments in some firms were tilted away from domestic biotechnology projects. The model also explains this variation in organization-level outcomes of movement contestation.