Modern Western society is a secularized society in which religion has become the concern, primarily, of the individual. As a result of the ongoing process of secularization, religion as a social institution has lost much of its societal relevance (Berger 1967; Luckmann 1967). In premodern societies, religion dominated peoples’ lives in all respects. Due to processes of differentiation, specialization, and the accompanying process of individualization in particular, religion was forced to retreat from many important sectors of social life. It has become a highly specialized institution of its own, like other major social institutions such as the family, education, economics, and politics. As a consequence of individualization, individuals are free to choose and practice their own religious convictions, just as they are free to choose their own political ideas, primary relationships, and so on (Beyer 1990). In this chapter we attempt to make an empirical assessment of some major theoretical notions of secularization. Four hypotheses are formulated, each based on the idea that modernization and individualization have continued in Europe in the last decade (1980–90). These hypotheses are empirically tested in ten West European countries using survey data gathered in 1981 and in 1990 by the European Values Group (EVG; see Ester et al. 1993; Halman 1991). It is further explored whether or not changes in basic values manifest themselves throughout modern society or are to be located within specific groups, for example, different age groups (Meulemann 1987). Differences in values may be caused by replacement of generations. Younger generations differ from older generations in many respects, and due to these intergenerational differences, values in society change. The other interpretation is that value changes are related to “life-cycle” or intragenerational changes: as one gets older, one’s basic values might change.