The 1995 Dayton Peace Agreement in Bosnia and Herzegovina instituted ethnic quotas between Bosniaks, Serbs, and Croats: the three “constituent peoples.” This institutionalization of ethnicity, criticized by some contemporary authors, is often seen as a creation of the peace agreement. Interestingly, several scholars deem such proportional representation a legacy from socialist times. But the existing literature lacks a historical perspective on the question of ethnic quotas. In addressing this issue, this paper reminds one of the existence of ethnic quotas, called the “national key,” during socialist times. A deeper analysis of the “national key” in the Socialist Republic of Bosnia and Herzegovina and of the ethnic quotas in the last two decades shows, interestingly, more differences than continuity. The article concludes that few similarities and more differences can be observed between the two periods, especially regarding the legal aspects of the “national key,” in ideological justification and in the conceptions based on parity or proportional representation.