This chapter shows the professionalization of the political class in Great Britain, a country that until the early 1970s was dominated by the amateur politician. Both major parties in Britain, the Conservatives and the Labour Party, created the crucial preconditions for the emergence and establishment of the political class, and it was in their interest to accelerate the process of professional i zation. Basic conditions have been carried through the steady increase of MPs’ salaries since the 1970s, an expansion of political occupations, and different mechanisms for career maintenance. Moreover, previous institutional reforms have not changed the composition of the p o litical class as much as they have strengthened the process of professionalization of the existing political class. Newly developed political networks within different policy areas foster the development of the career politician, who early in his or her career e n ters politics and wants to stay there; the networks facilitate both entry into politics and maint e nance within the political class.