Based on accounting reports kept by a real estate property manager and on census data, this article analyses residential mobility in Lyon between 1891 and 1968, and especially its evolution after the rent control and tenant protection legislation of 1914. It shows the importance of subletting between the First and the Second World War. Thanks to the subletting phenomenon, residential mobility does not decline as much as is often said. It also has important consequences on social change and social structure in the buildings examined.