Tracing transformations in the way that humanitarian organizations respond to insecurity in the field, this article examines the bureaucratization and professionalization of security in relation to intraorganizational struggles between humanitarian professionals. Whereas some advocate for the triumph of remoteness and bunkerization as organizing principles of humanitarian action, others challenge the imposition of security as a humanitarian logic of practice through acts of nonconformity. These tensions are illustrative of professional struggles over how to do and think humanitarian action. In articulating a sociological and transversal reading, this article points to the heterogeneity and divisions structuring the humanitarian space. To provide empirical insights into the bureaucratic work practices of headquarters professionals and the everyday practices of frontline humanitarian professionals, this article draws upon an analysis of humanitarian security manuals, interviews with humanitarian professionals, and field observations in Port-au-Prince. The article sheds light on the development of the humanitarian profession and on the novelty of the work practices of humanitarian security professionals, while contributing to debates on bunkerization and the literature on transnational professionals.