My research explores policy-making in the UK Department for Environment, Food and Rural Affairs (Defra). I focus on the part of Defra that seeks to control exotic animal diseases such as Foot and Mouth Disease and Avian Influenza. The research investigates how civil servants make policies to control animal disease, how scientific expertise is used in decision-making, and the differences in styles of policy-making that occur during disease outbreaks compared with 'peace-time'. In contrast with conventional policy analysis, my research takes an interpretive approach to the study of policy-making. The emphasis of my analysis is on the understandings that officials hold about aspects of policy-making and how these understandings influence their behaviour. I gathered accounts from Defra officials and their advisers, using participant observation and interviewing, about what it means to be a bureaucrat and to provide expertise. Drawing on insights from organizational sociology, I treat these accounts as stories about policy-making with not only explanatory but performative power. Using John Law's (1994b) concept of 'modes of ordering', I view policy-makers' stories as organizing narratives that structure interactions and generate' organizational materials and realities. I argue that three modes of ordering can be identified in Defra's exotic disease division: rationalism, bureaucracy, and expediency. These three modes interact, overlap and contradict one another as Defra staff seek to make sense of the organization and their role within it. I conclude that the differences between these three modes of ordering account for differences in the way that policy-making is organized over time and between policy contexts. During disease outbreaks, for example, Defra officials think of themselves as 'heroes' and act accordingly, while during 'peace-time; they consider themselves bureaucrats or rational decision-makers to justify their inability to achieve policy outcomes.