This article analyzes five electoral reforms that were enacted in Chile between 1958 and 1962. These reforms introduced the Australian Ballot, and also changing the rules about electoral pacts. By using an analytical frame based on recent literature, the article focuses on the “who and why” of these reforms, chiefly which incentives did the political parties have in order to pursue these legal changes, and the objectives they tried to achieve through them. To analyze the aforementioned, the research concentrates on the political context of the reforms, their political and parliamentary discussion. The paper argues that these five reforms are related to two main objectives: the intention to improve and/or hurt the political interests of specific actors, and to overcome legitimacy problems of the party system.Este artículo analiza cinco reformas electorales chilenas de 1958 y 1962, relativas a la regulación y supresión de los pactos electorales y el establecimiento de la Cédula Única. Utilizando un marco analítico elaborado a partir de la literatura comparada reciente, se estudia el quién y por qué de esas reformas, esto es, los incentivos que tuvieron los partidos para impulsarlas y los objetivos que persiguieron con ellas. Para ello, se estudia tanto el contexto político en que se realizaron, como el debate político y parlamentario a que dieron lugar. Se argumenta que las cinco reformas analizadas se vincularon a dos objetivos principales: favorecer y/o perjudicar los intereses de actores específicos y superar la creciente deslegitimación del sistema partidario.