Chapter 2 offers a novel conceptualization of administrative styles. Depending on dominant strategic orientations shaping administrative routines, we identify four ideal types to systematically assess IPAs’ policy influence: a servant style, an advocacy style, a consolidator style, and an entrepreneurial style. In addition to this conceptual innovation, we offer a theoretical framework accounting for the variation in administrative styles across different international bureaucracies. We argue that the variation in administrative styles across different organizations can be explained by two factors, namely the perceptions of internal and external challenges.