This chapter documents the role that women played in the computing field in three different European countries from the late 1960s into the early 1990s: Finland, a latecomer to the computer industry which was then deemed of national importance; France which boasted several computer manufacturing companies, and where IT service companies played an important role in the early history of computing; and the United Kingdom, also involved in computer manufacturing, but where the public sector played a major role. We will see that despite national differences, similarities exist concerning the role women played in the computer industry and that the masculinisation of the profession can be attributed to similar causes. Initially jobs were considered unskilled and marked out as women's work. When women acquired the necessary skills to play a more important role, various forms of discrimination slowly discouraged them from staying in computer science. The study of these three countries at the moment when computing was introduced into the public and private sectors and became a major tool for management and strategic decisions, shows how software activities were socially constructed as masculine.