Our reserach contributes, in particular, by conceptualizing international bureaucracies as autonomous actors that need to be distinguised from international organizations. Our work traces empirical manifestation of their influence, which can be found in cognitive, normative and executive dimensions of global governance. We also provide explanations for the influences as well as variations in influence across different types of international bureaucracies. Findings highlight the significance of internal factors such as organizational culture, expertise and leadership as well as the problem structure within which bureaucracies operate. By contrast, institutional design bear limited explanatory power. Still, the knowledge of international bureaucracies is hardly sufficient. For example, the causal relationship between the actions of the executive top and the external influence of international bureaucracies remains poorly undrestood. Therefore more comparative and systematic empirical studies will help test furteher hypotesis about the general conditions of bureaucratic influence.