This Dissertation, written at the Department of Political Studies in the School of Social Sciences, is submitted in fulfilment of the requirements for the Degree of Doctor of Philosophy (Ph.D), to the Faculty of Humanities at the University of the Witwatersrand, Johannesburg, South Africa, September 2017 / The purpose of this study is to examine the causes of ideological moderation in the South African party system in the post-1994 period. Previous research stresses the non-left-right feature of politics and when it recognises the centrist feature of major parties and moderation of the party system, the causes of the latter are unexplained. The deficiency in previous research is that moderation and limited left-right disagreements as fundamental causes of broader political dynamics are overlooked — moderate systems foster political consensus and democratic stability. In this study I critically examine three theoretical causal variables that account for moderation: the electoral system, the electorate, and the dominant party. This study relies on a measurement of party system fragmentation, and voter and party system polarisation, as well as an intensive qualitative assessment of the ANC. The evidence is based on a number of nationally representative surveys that measure public opinion; interviews with political party leaders and representatives, and officials from labour and business; and document analysis. The finding is that the ANC as the dominant party is the main driver of moderation in the party system. Coupled with electoral dominance, the centripetal, non-dogmatic, pragmatic and flexible tendencies that characterise the ANC permit the party to induce and stabilise party system moderation. This study: develops a causal framework for understanding moderation; builds on previous research about the centrism of major parties and the moderation of the party system (both quantitatively and qualitatively); departs from the argument about the fragmented and rightist nature of the opposition bloc and the race-based approach to the electorate; and extends the debate about the ANC by arguing that left-right movement occurs within centrist terrain, and that the party is not an amorphous or client entity but a clearly defined one. I also add to: the growing body of knowledge that finds no necessary connection between proportionalism, extremist party positioning and polarisation; the idea that party system polarisation is less reflective of voter polarisation; and concur with previous research that argues that the role of a pivotal centre party is critical for the party system. / XL2018