Since 1989 six Central and East European countries have held competitive elections under 17 different electoral systems. After some experimentation, the new electoral systems, adopted on the initiative of noncommunist parties, provided for proportional representation, with legal thresholds designed to protect the new parties from smaller, more recent, and more extreme formations. These legal thresholds favored noncommunist parties initially but subsequently appeared to facilitate a return of postcommunist parties to power. A multivariate model of the effect of electoral system thresholds in 13 elections confirms that they contributed to disproportionality but fails to confirm that they consistently favored either former communist or noncommunist parties. Further analysis reveals that legal thresholds have exaggerated the effect of volatility in the electorates on the representation of parties in parliament, causing systems of proportional representation to behave more like single-member plurality systems.