Résumé : We propose an in-depth analysis of a specific custom designed to ensure the recovery of debts in the late Medieval Low Countries, using personal sureties (conditional hostages) having to sojourn in an inn to guarantee the contract-enforcement, called the leisting. Its use was initially restricted to aristocratic circles as we show in our first case study concerning a (public) debt to finance territorial expansion of the count of Guelders at the end of the 13th century. We show that the leisting was not always sufficient as more possessory sureties (tolls revenues, incomes from fines and landed estates…) were added in a second loan contract. We stress also the role of Piedmontese moneylenders and how the loan was later sold to the count of Flanders who will make of political use of it. The use of social capital to access capital markets was nevertheless found in several contracts during the 14th and 15th centuries. In our second and third case studies we show how this technique developed within a more mercantile environment. We analyse the case of Kampen during the 14th century, a city that faced both a commercial and urban development. We identify an important use of the leisting technique during this phase of urban development hinting at a regulatory desire of city authorities to avoid speculation on houses and grounds. Lastly, we analyse the case of the city of Brussels during the first half of the 15th century. Here we rely on archival sources allowing us to pinpoint the social profile of those innkeepers so central in this mechanism. They were often brokers as well as hostellers and belonged to the high strata of the city. We discuss the efficiency (and the longue durée) of this practice from a neo institutional perspective.