Resumen: This paper presents a methodological approach to the study of the increasingly efficient commercial and banking firms in late medieval Europe, based on the structural analysis of two major Mediterranean firms that operated from Zaragoza and Barcelona in the first half of the fifteenth century. The analysis of the cooperative mechanisms deployed by the socio-economic elite of the Crown of Aragon is brought to the foreground with special emphasis on human capital strategies, such as those reflected in the recruitment of commercial agents. We discuss a number of examples drawn from notarial records, account books and commercial correspondence in order to bring to light not only commercial relationships but also kinship and friendship ties. Idioma: Inglés DOI: 10.7410/1444 Año: 2020 Publicado en: RiMe – Rivista dell’Istituto di Storia dell’Europa Mediterranea 7, 3 (2020), 111-153 ISSN: 2035-794X Tipo y forma: Artículo (Versión definitiva)