The main topic of this article are the motives that led to the adoption of lustration laws in the Czech Republic, Poland, and Serbia, and their social functions. In the opening section, lustration is placed in the wider framework of dealing with the past and two possible approaches to the phenomenon are discussed: to take it as part of the broader process of decommunization, or a measure of transitional justice. In the next section an attempt at defining the concept of lustration is made, with a view to eliminating some ambiguities surrounding it. Subsequently, two partially complementary theoretical models explaining the occurrence, form and severity of dealing with the past and lustration are presented. After that comes the description of the socio-political context at the time of the adoption of lustration laws in the three countries and identification of political and ideological forces that have supported or challenged it. Finally, the article attempts to answer the question whether lustration is a legitimate measure of settling historical justice, overcoming the legacies of socialism, a way to strengthen liberal democracy, or merely a tool in political struggles for power.