This chapter investigates how formal autonomy and informal administrative working styles of international public administrations (IPAs) are interrelated empirically. Recent research on IPAs identified a paradoxical constellation. Some IPAs with low structural autonomy, such as the Organization for Security and Co-operation in Europe Secretariat, are able to compensate this restriction by developing an entrepreneurial administrative style with emphasis on initiating new policies and sound internal management (paradox of weakness). Other IPAs, such as the formally autonomous European Commission, were found to anticipate member state control and voluntarily restrict themselves to a more passive servant style (paradox of strength). This finding raises the question whether the two paradoxes are idiosyncratic features of the two cases or a more universal phenomenon of international bureaucracies. To answer this question, this chapter introduces the concepts of structural autonomy and administrative styles and lay out a strategy for their measurement. It compares the empirical pattern of autonomy and style in eight IPAs. It concludes with some propositions about potential consequence for international bureaucratic influence.