A growing body of literature has emerged that examines the contributions of mid-level institutions of accountability (e.g., public ministries, federal police, and electoral courts) in curbing corruption. Notably absent here is the Defensor del Pueblo (ombudsman). This study posits that, under the right conditions, these nonsanctioning bodies have several tools at their disposal that can be leveraged against state actors to reduce corruption. The ombudsman's unique links to the public (or principal) and external actors allow it to function like a "fourth estate," but the strength of the office to act as an effective deterrent to corruption is endogenous to the system and actors that created this office. This study conducts a two-stage least squares regression analysis for 17 Latin American countries (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011), provides support for these expectations, and suggests that the ombudsman is beginning to deliver on its promise, at least with respect to corruption.Los estudios sobre la corrupci on se han enfocado en las contribuciones de las instituciones de nivel medio (por ejemplo: ministerios p ublicos, la polic ıa federal, y las cortes electorales). No se ha tomado en cuenta el papel jugado por la Defensor ıa del Pueblo. Este estudio propone que, bajo las condiciones apropiadas, la Defensor ıa, una agencia que no tiene el poder de sancionar legalmente, puede usar varias herramientas para disminuir la corrupci on pol ıtica. La Defensor ıa funciona como el 'cuarto poder' ("fourth estate") porque mantiene nexos unicos con el p ublico (el principal) y los actores externos. Sin embargo, el poder de la Defensor ıa para combatir la corrupci on es end ogeno al sistema pol ıtico. Este estudio examina a las contribuciones de la Defensor ıa usando una regresi on de dos fases para 17 pa ıses latinoamericanos (2000-2011) y concluye que esta agencia est a empezando a tener un impacto positivo cuando se trata de la corrupci on pol ıtica.