Since the late 1980s historians of the family have been interested in the socio-demographic analysis of the role of domestic service in European societies during the Ancien Régime. These scholars have been concerned with the consequences of life-cycle service since it appeared that a significant proportion of Europe's inhabitants were in service at some point in their lives. This proportion was highest in countries of Northwestern Europe, such as England, where between 10 and 12 per cent of the population worked as servants, usually while young, moving readily from one household to another. This process began at an early age, around adolescence, and tended to end with a change in occupation, generally just before entering into marriage, in other words, prior to forming a separate family unit. By relating the mobility of servants to the specific characteristics of the marriage-formation model, historians have been able to highlight the contribution of domestic service to social and familial reproduction. Encouraged by their results, the next step for social historians was to elaborate an explanatory model of this system of family reproduction. Although the model offered was derived from the behaviour of a concrete social and demographic structure which was basically Northern European, it was nonetheless presented as the principal model for all of Western Europe.