The merits and shortcomings of various electoral systems for post-conflict elections in divided societies have been debated extensively. This paper aims to contribute to this debate by moving ethnic composition, i.e. the number, size and settlement patterns of ethnic groups in a society, centre-stage as a context condition for list proportional representation, majoritarianism and single member plurality. An overview is then provided of the electoral systems used in 23 post-conflict parliamentary elections conducted in divided societies, and we discuss to what extent they correspond to the requirements of a society's ethnic composition. © 2013 © 2013 The Editor of Ethnopolitics.