A ballot reform was adopted in Colombia in early 1990s. The traditional paper ballots, which were printed and distributed by parties, were replaced by an Australian ballot—an office-centered design in which the electoral authority was responsible for its distribution. The article examines about 5,800 department-level legislative lists, during 10 election cycles between 1970 and 2002, to evaluate the consequences of the reform. The evidence shows that candidates expanded the geographical scope of their campaigns after the ballot reform and that party bases became more geographically dispersed. Moreover, the evidence indicates that the new ballot undermined the power of party leaders to coordinate factions, resulting in a considerable increase in the number of lists—and with it, of wasted votes. These findings suggest that an arguably minor reform, such as the adoption of a new ballot form, may have major implications for democratic representation.