This chapter explores the extent to which the cleavages underlying voting behaviour in the Irish party system have changed since the 1970s. The divisions within the party system can be seen as between Fianna Fáil and Fine Gael, between Fianna Fáil and the rest, between Fine Gael and the rest (leaving aside Fianna Fáil), and between left and right. The basis for voting analysed are class, religion, party identification, and ideology. The weight of each on each division is traced over time. While the party system has clearly fragmented, and the left has grown in size, the importance of each of these factors has not changed significantly, either since the 1970s, or just since the economic crisis. Various explanations for the lack of change are discussed, including the persistence of candidate centred voting, localism, and how party competition has tended to obscure real policy differences.