In this article, we evaluate workforce diversity in the United Kingdom civil service by investigating the organisational determinants of the representation of women, black and minority ethnic and disabled people in central government departments. To do so, we draw on workforce data for 21 departments between 2007 and 2009. Our study reveals the presence of statistically significant variations in rates of representation across departments and that key organisational characteristics, such as size, administrative, part-time and temporary employment, and autonomy account for a sizeable portion of this variation but often affect under-represented groups differently. Theoretical and practical implications are discussed.