In the last decades value research has produced a vast number of theoretical concepts. However, it is unclear how the different value theories relate to each other. This study makes a first step toward a systematic comparison of value theories. It focuses on the individual level of the two approaches that are, at present, probably the most prominent in international research - the theory of basic human values of Shalom Schwartz and the postmodernization theory of Ronald Inglehart. Using data from the World Value Survey and the European Social Survey for West Germany we assess both the internal and the external validity of the two accounts. The results indicate that both value theories have different strengths and weaknesses. Whereas the Inglehart account has lower internal and weaker construct validity, the Schwartz account is somewhat less consistent in its predications. Nevertheless, both value conceptions are able to explain a substantial share of variation in specific attitudes and behavior.