Spanish Abstract: Este articulo analiza la actividad regulatoria y sus motivaciones considerando algunos conceptos de la nueva economia institucional. La elaboracion de mejores marcos regulatorios da legitimidad a la accion del Estado. Sin embargo, dicha legitimidad solo se logra cuando esos marcos son eficaces y eficientes para conseguir los fines que se buscan,como corregir fallas de mercado, resolver problemas de equidad o crear entornos mas competitivos.English Abstract: The purpose of this paper is to analyze, with a new institutional economics framework, regulatory activity and its motivations. Better regulatory frameworks contribute to create an environment of legitimacy for the actions of the State. Nevertheless, this legitimacy can only be achieved by ensuring the efficiency and effectiveness of such frameworks in relation to the aim pursued such as correct market failures, reduce inequity failures, or generation of more competitive environments).