This paper presents a natural experiment, comparing the effects of two-round (TR) and proportional representation (PR) voting rules in French cantonal and regional elections. A series of rigorous model estimations demonstrates that the two electoral types clearly produce distinct outcomes. TR systems bring about less extremist party voting, less party competition, and perhaps less vote turnout, when compared to PR systems. These findings call into question the lack of attention to TR effects, and the notion that TR is not really a distinct electoral form.