The Saint-Simonians were a group of young engineers and doctors who proposed original solutions to the social and banking crises of the early nineteenth century. They were unique in the 1820s in attracting women, including workers, into their movement, and attempting to change the world through love, including the sexual 'liberation' of women. Some metamorphosed from idealistic reformers to create the first socialist groups in France, while others spearheaded bank reform, railway building and urban transformation in the 1850s. They took the lead in the colonisation of Algeria, in popular journalism, business, and in organising international exhibitions. They planned the most notable engineering project of the time, the Suez Canal, and a project that took over a century more to be completed, the Channel tunnel. Through an examination of the lives, ideals and activities of these men and women, Pilbeam analyses the influence of the Saint-Simonians on nineteenth-century French society.