Post-Soviet nations exhibit a variety of regime types, from democracy, as in Estonia, to dictatorship, as in Belarus. Some nations have undergone transitions from democracy to dictatorship, while others the reverse. New time series data on regime institutions reveal in more detail the post-Soviet dynamics of these transitions and the way in which the Soviet legacies and the geopolitical dominance of Russia remain critical. In this chapter we study the evolution of governmental institutions in post-Soviet former republics and compare their transitions and institutional sequences from Soviet times, relying primarily on the unique data set MaxRange on political institutions in nations of the world. In pioneering analyses it is shown how improved methods of comparative politics and use of categorical data in evolutionary tree analyses can help us understand why and how post-Soviet nations differ in transitional dynamics.