This chapter discusses the fundamental concept that expertise gives rise to consultants before outlining different views on the nature of consulting work and how they relate to the processes of contemporary public policy-making. A framework for identifying the nature of policy consulting work will assist with assessing the research question of the influence of such consultants on public policy and on the policy-making process. The use of both quantitative data and properly grounded qualitative research is essential to the quality of the basic research. Governments seeking policy advice require individuals to have a comprehensive understanding of the field in question but also an understanding of the workings of government and the policy process more generally. In relation to the activities of the Australian Public Service the roles played by consultants vary from that of the expert giving very specific technical advice to organisations to that of the confidante giving open-ended support and assistance to a political or departmental leader.