This article traces the development of the role of human rights and democracy in determining admission to three European organizations: the Council of Europe, NATO and the EU. Despite the different functions that each organization performs, they have all assumed that prospective members must comply with human rights and democratic conditions. This is evident in both the organizations' constituent instruments and related membership documents, and also in the recent admission practice of the three organizations. But the membership practice also indicates that since their establishment the organizations have not always applied these conditions rigorously – thus there is a tension between the organizations' desire for homogenous universality (getting better) and heterogeneous universality (getting bigger). The admission practice also reveals a number of problems with the use of human rights and democratic criteria, including inconsistencies in the application of the criteria between applicants and existing members of the same organization, and inconsistencies in the application of the shared criteria across the three organizations. In the end, the development of the common membership criteria of human rights and democracy highlights both a degree of flexibility in admission decisions, as well as a progressive change in the functions of each organization.