The purpose of this project is to assess one of the most controversial doctrines in contemporary political thought. In public debate as well as in political theory, it is often argued that the state must be neutral regarding citizens' values, or more specifically, not take a stand regarding what constitutes a good life. The question is, however, what such neutrality in the domain of values actually implies. The purpose of this project is hence to attempt to apply the principle of value neutrality, i.e., to investigate which implications it might have when it comes to some important political and moral questions. There are a great number of issues for which this kind of neutrality might play a role, such as family, schooling, equity or drug policies. In this case, however, we will apply this normative principle in an even more controversial and currently debated question, namely, marriage. Should the state regulate the relationships of couples of the same sex? Should polygamy be allowed? Is marriage between close relatives to be illegal - or does the principle of value neutrality demand that such relationships be given the same legal conditions as traditional couples? What kinds of relations should the state recognise as marriages? Can the institution of marriage be justified if neutrality is to prevail, and if so, which groups are to be eligible? These kinds of questions are currently receiving ever-more attention, and it is important that they receive principled answers.