A common view is that one of the main goals for countries should be to be democracies. However, countries should not be satisfied when they had achieved democratic status. One of the subsequent goals should be to establish a high degree of the quality of democracy. Of course this goal also applies to well establish democracies. For the legitimacy of a democratic system it can be seen that a high degree of quality of democracy is important, and a low degree of quality of democracy can be seen as a serious democratic problem. For example political participation through voting can be seen as a cornerstone in a democratic system. If voter turnout is low the legitimacy of the election and the democratic system can come into question. According to that, this study will compare and explain the variation of the quality of democracy in the stable democracies in the world. 1 A total of four dimensions of the quality of democracy will be included; participation, competition, equality, and rule of law. An index will be constructed which includes those four dimensions of the quality of democracy. To explain the variation in the quality of democracy an explanatory model will be developed. The result from the study will answer if there are cultural factors, historical factors, political institutional factors, physical factors or socioeconomic factors or a mix of these factors which can explain the variation of the quality of democracy in the world’s democratic countries. Earlier research hadn’t agreed on one definition of the quality of democracy (see eg Altman and Pérez-Liñán 2002, Diamond and Morlino 2005, Lijphart 1999 and Stålfors 2008) and they hadn’t used the same dimensions and indicators when they had measured the quality of democracy. This is supported by Andreev (2005, 4) who stated that:“students of democracy have not been very rigorous when selecting and combining various indicators of how to measure the QoD.” On that basis it is difficult to compare the different research results concerning the quality of democracy when different definitions and measurements have been used in the various studies; also a limited number of countries had been included in previous research. This study will not focus on some particular democracies as for instance wellestablished democracies or democracies in some specific region. The study will focus on all stable democracies in the world. The main purpose of the present study should therefore be seen as seeking to provide a contribution to explaining the variation of the quality of democracy in the stable democracies in the world. However to fulfill the main purpose I will work with two sub purposes. The first is to develop an explanatory model for the quality of democracy. The second is to develop an index which measures the quality of democracy.