This dissertation explores how and why senior ministerial bureaucrats assisted the Nazi regime in pursuit of its ever-radicalising ideological agenda by examining both the practice of administration under National Socialism and the biographies of its practitioners. Focusing exclusively on those who led government ministries – the Staatssekretäre – it will argue that whilst the bulk of the Third Reich’s administrators identified with its agenda on some level, this only partly explains their readiness to implement it. Of equal importance were the structural imperatives, common in all bureaucratic organisations, to conserve or expand departmental portfolios within an increasingly fragmented ‘polycracy’ of competing government departments. Combining the historical method with theories and perspectives from political and administrative science, systems theory, organisational theory and sociology, it will thus offer a structural understanding of bureaucratic conduct under Nazism, albeit one that places agents at the very centre of the analysis. The dissertation is broken into three sections. The first will provide both a prosopographical and collective-biographical examination of the Staatssekretäre and their experiences before 1933, focusing particularly on a) the factors that rendered them sympathetic to the NSDAP’s message, and b) the readiness of civil servants to serve the Weimar Republic despite their growing hostility towards it. This last point sets the tone for the rest of the dissertation, for it shows that political identification with a particular regime was not a necessary precondition for serving it. And in Section II I revisit civil servants’ response to regime-change, this time in 1933, showing again how they processed the demands of the political leadership, ‘coordinating’ themselves in pursuit of a more radical political agenda. Section III, finally, explores some of the reasons why ‘self-coordination’ was the typical response to regime-change, and with that reveals the logic that informed the practice of administration more generally. Following a brief theoretical chapter outlining why bureaucrats are structurally compelled to both preserve the organisations (ministries) they represent and advance their interests, debtates between the Staatssekretäre over the Third Reich’s policy agenda will be examined. For these debates suggest that the actual practice of administration, as many theorists contend, was informed less by the political or ideological beliefs of its practitioners, and more by the desire to shape policies in ways that served the conservation and, where possible, expansion of departmental portfolios.