Financial practices are not only about money. This paper discusses how people living and working in the Mexico/United States borderlands weave their economic lives by combining, associating, and disassociating formal and "informal" currencies. We base our analysis on transactions carried out by women who commute regularly between the twin cities of Mexicali and Calexico,detailing their financial practices; the frameworks of calculation they employ; and the social, cultural, and financial mechanisms they and their families use to cope with their daily lives. These include the use of monetary and non-monetary calculations and resources, different types of indebtedness and forms of reciprocity. Such findings reveal mistakes in the tenets upon which much anti-poverty and financial aid programs are based. A focus on people's use of particular calculations, resources, and social relations will help substantiate better alternatives that can be implemented in supporting their economies.