Direct democratic institutions allow citizens to directly influence policy decisions. They have the potential to lower the influence of legislative and executive bodies while allowing citizens to do more than periodically elect representatives. The research question of this paper asks: What explains the adoption of direct democratic institutions (DDIs) in representative democracies? I argue that the adoption and extension of direct democracy is fueled by the electoral distortion caused by majoritarian elections. Groups that cannot translate electoral power into political power seek to change the institutional setting. The analysis is carried out on a novel data set of constitutional changes in all Swiss cantons during the 19th century and provides insights as to how and when DDIs are introduced or extended.