Recent studies show that the effects of electoral systems and ethnic cleavages on the number of parties in emerging democracies differ from those effects observed in more established democracies. Building on recent arguments maintaining that the quality of democracy improves with experience, we argue the reason for the differences in the findings between established and emerging democracies is that the effects of these variables on the number of parties differ according to a country’s experience with elections. To test this argument, we analyse party system fragmentation in 89 established and emerging democracies and the conditioning effects experience with elections have on the effects of district magnitude, ethnic cleavages and variables relating to the presidential party system. The results show that the effects of institutional and social cleavage variables differ substantially between emerging and established democracies, but these effects begin to approximate those seen in more established democracies with additional experience with elections.