Often person-organization fit in terms of value congruence is mentioned within the scope of the homogeneity hypothesis, stating that when organizations mature, they are increasingly populated by similar members (Bretz & Judge, 1994). This process can be due either to individuals who change their jobs to coincide better with their values or to individuals who adapt their values to coincide better with their jobs. These two opposing streams of literature, the attraction-selection-attrition framework (Schneider, 1983, 1987) and the socialization (e.g. Cable & Parsons, 2001; Chatman, 1991), are tested. A total of 142 respondents, graduated as a teacher in 2004, participated in a longitudinal survey research with a two years’ time interval. Results of paired samples T-tests stating that over time changes in work values become apparent and that perceived value congruence increases with tenure can be interpreted as evidence for the socialization thesis. Furthermore, results of logistic regression analyses confirm that the lower the perceived match between own and organizational values at entry, the more likely it is that someone leaves the organization. We can conclude that the resulting homogeneity originates from a combination of the ASA and the socialization process. After a severe self- and organizational selection, individuals enter the organization with specific work values and a certain perception of fit. After entry, additional organizational forces, namely socialization practices, serve to enhance homogeneity. The personal work values undergo small changes and the perception of fit with the organization grows. Yet, when individuals’ initial fit is rather low, they are more likely to get attritioned out of the organization, as the ASA framework suggests.