Thesis: For decades, economists have been interested in studying why and how agents support eachothers, giving a special place to the analysis of private income transfers. Recent applicationsinclude very diverse topics such as: the analysis of capital accumulation, social cohesion andsolidarity, market insurance and interest rates, risk-coping strategies against negative shocksand government policies.The present dissertation analyzes how inter-household transfer decisions, international remittancesand intra-household transfers contribute to shape five fundamental aspects of development:(i) social interactions, (ii) market and household work, (iii) spending patterns, (iv)nutrition and (v) health.Three research questions are addressed using applied data from Colombia, Ecuador and Peru,and multiple econometric techniques. First, is there a relationship between inter-householdtransfer dynamics and distance between donors and receivers? Second, do remittances asymmetricallyshape labor supply responses depending on people’s characteristics? Third, dointra-household transfers influence spending patterns, nutrition and health outcomes?Results suggest that private income transfers play a key re-distributive role, shaping agents’living standards and improving individual and social well-being. In contexts of economic deprivation,where social safety nets are scarce, informality is at stake, institutions are highlyfragmented and the public sector is weak, money and in-kind help from other households orindividuals constitute crucial livelihood strategies to get through the economic world. Thus,enhancing our understanding of this dimension of social behaviors is a must.