Today, issues of communication and presentation of expert knowledge have grown to be a central part of the work of the modern economist engaged in public expert advice. Contemporary economic experts are not only expected to be specialists within their field of expertise, but also increasingly to engage in making their expert knowledge available to a general public. This new public role of the expert frames what in expert studies and Science, Technology and Society Studies (STS) is called a ‘third wave’ of science studies (see Collins and Evans 2002; Maasen and Weingart 2005; Irwin and Wynne 1996). The central focus of the chapter is to look into the multiple transformations which expert knowledge undergoes as it interacts with political decision making as well as with a general public.