Electoral behavior has changed considerably over the last few decades. The Netherlands are exemplary of how the cleavage structure has waned and how this has led to a weakening of the bonds between parties and voters and to higher levels of electoral volatility. Christian democratic and social democratic parties are most affected by these changes, because of their strong roots in the cleavage structure. The alterations in electoral behavior are generally assumed to be evolving gradually through a process of generational replacement. Composition effects on the one hand and a weakening of the impact of socio-structural factors, partly caused by cognitive mobilization on the other hand are considered to be the mechanisms behind this generational change. This paper tests these assumptions with regard to the Netherlands on the basis of the Dutch Parliamentary Election Surveys, 1971-2010. The findings indicate that while some variation between different birth cohorts is visible, most of the differences in voting for both of these parties, however, are situated at the level of election years. Furthermore, with regard to what drives change over time, the analyses indicate that while composition effects and changes in the effects of socio-structural variables are of some importance, cognitive mobilization is not causing the change observed.