Major electoral reforms have been strikingly frequent in Latin America since the beginning of the third wave of democratization. Such reforms include the adoption of runoff formulas for the election of the president, changes in tenure and reelection rules, the replacement of proportional representation by mixed-member rules, alterations in the number and magnitudes of electoral districts, and the creation or elimination of legislative chambers as well as modifications to their size, to name a few important instances of electoral change. Such major reforms have not been simply the result of regime change, nor have they slowed down as democratic regimes have become more stable in the region. Instead, the rate of reforms has remained constant since the 1980s – the result of cyclical crises and weak institutions, features of day-to-day politics in Latin America. In this chapter, we seek to understand what determines the enactment of major electoral reforms in the region.