For electoral systems to exert expected effects on voters, candidates, and parties, institutions should be durable and consistent. If political actors believe that the rules are likely to change, they may pursue strategies and tactics that seem to be at odds with the electoral system’s underlying incentive structure. This chapter evaluates how changing electoral rules in a transitional, post-Soviet society has affected political outcomes. Ukraine serves as an important case for scholars of electoral systems to illustrate consequences of institutional instability. The specific rules that Ukraine has used, coupled with a tendency to alter electoral systems after one or two elections, has promoted an inchoate and volatile party system and short-term strategic planning by politicians.