As a thesis dissertation, I propose a set of three studies regarding financial inclusion and financial development in Colombia. The first paper (job market paper) analyze the massive use of an informal lending called gota a gota (a type of credit offered by loan sharks) in Colombia. It seeks to evidence that this credit arrangement is used as a commitment device by the borrowers to keep under control its personal finance, consumption and investment. Understanding the informal arrangements and whether they produce suboptimal outcomes, helps to think in potential improvements to the formal commitment contracts or the creation of new ones. This paper is related with a new branch of literature that studies the micro foundations of credit markets, in particular the behavior of the borrowers (e.g. Gugerty, 2007, Ambec and Treich, 2007; Bauer et. al. 2008, Basu, 2011). This paper intends to be a novel approach since there are few studies investigating loan facilities as commitment devices (Bauer et. al., 2008, Fuwa et. al., 2015) and to my best knowledge there is only one study using this approach with informal lending facilities (Fuwa et. al., 2015). The second paper will analyze the expansion of the gota a gota arrangement from Colombia to other countries in Latin America. The purpose of this paper is to study the determinants of the expansion of Colombian loan sharks emphasizing the aspects related with the violent enforcement methods. The second paper seeks to contribute with an empirical exercise of the network analysis of criminal structures and the development of parallel activities such as informal finance. Finally, the third paper will study the expansion of the Colombian formal institutions to Central America and the benefits of these new links to the economies and its trade."