Published online by Cambridge University Press: 07 January 2015
Current theories on institutional change tend to interpret it either as the result of long-term gradual trends, or of disrupting shocks following periods of punctuated equilibrium. Less is known about the moments in which change is more frequent. Focusing on the short-term determinants of reforms of core democratic rules in consolidated democracies, the article shows that proximate shifts in the electoral arena have a distinctive impact on the number of institutional reforms that are adopted in a legislature. Using the empirical and theoretical findings of the literature on electoral reform, the article develops a model tested in statistical analyses aggregating a large sample of institutional reforms in Western European democracies between 1990 and 2010. The results show that rising electoral uncertainty measured by volatility, and the change of preferences of the actors in power measured by the advent of new forces in government lead to the adoption of more institutional reforms. These results appear consistent when some categories of reform are added or subtracted, giving confidence that this model can be applied to a wide range of institutional reforms.