This paper examines the emergence of mechanical engineers in the technological and social context of professionalization in England. Despite their technological progress, most steam engine wrights and machine tool builders were individual workshop owners working to order in the early 19th century. In the 1830s and 1840s, however, the railway boom produced so called railway engineers by providing them with some managerial experience as the canal building did in civil engineering. Railway engineers played a dominant role to establish the Institute of Mechanical Engineers(IME) in 1848. It was IME that stated what is a mechanical engineer and helped its members be in the similitude of the civil engineers in social and technological activities.