We provide descriptive evidence on the characteristics of a household’s extended family network using data from the Progresa social assistance program in rural Mexico. We exploit information on the paternal and maternal surnames of household heads and their spouses and the patronymic naming convention to identify the inter and intra generational family links of each household to others in the village. This provides an almost complete mapping of extended family networks structures across 506 Mexican villages, covering 22,000 households and over 130,000 individuals. We then provide evidence on – (i) whether husbands and wives differ in the extent to which members of their extended family are located in geographic proximity; (ii) the characteristics that predict the existence of extended family links; (iii) the similarity of households within the same family network in terms of their poverty, and how this differs within and between generations of the extended family.