Why do political actors pass legislation that seemingly hurts them? Lustration laws limit access to public offi ce of the ancien regime's collaborators and hurt members of post-communist parties in East-Central Europe. So why has lustration in Poland, Hungary, and Bulgaria been passed when post-communist parties held parliamentary majorities? Why did the postcommunist party in Romania switch from no-lustration to pro-lustration after the 1992 elections? We explain this phenomenon by electoral timing and rules of rocedure in legislatures. Specifi cally, we develop an agenda-setter model with a finite number of parties, imperfect information, and multiple potential medians. Our main argument can be summarized as follows: Suppose that the Postcommunists do not introduce any lustration bill and then lose proposal power in elections. If Anti-communists come to power, they are sure to introduce a harsher bill, and the median of the legislature may prefer such a bill to a no-bill status quo. Post-communists can prevent such a scenario by implementing a mild bill themselves. If they manage to appease the new parliamentary median, they will block a harsher bill that would be implemented after they lose power. Additional results show how electoral perspectives and uncertainty affect and modify this typical scenario. We test our model with an exhaustive analysis of all cases from East- Central Europe that meet our assumptions that a Postcommunist party is in power and no lustration bill is already in force.