In applying constitutional review, post-communist constitutional courts are affected by the existing political and institutional environments, as well as by their own institutional capabilities. However, our understanding of the activity of the post-communist constitutional courts remains incomplete because the existing research fails to consider how the institutional changes on these courts affect their decision-making behavior. In this study, I examine the activity of nineteen post-communist constitutional courts during the 1992-2006 period. I use an aggregate, time-series measure of judicial institutionalization to show that higher levels of institutionalization enhance these constitutional courts' ability to pursue their policy goals and influence the degree to which they invalidate policy choices of other major political actors, while lower levels of institutionalization limit the courts' impact on legal and political issues. The findings of this analysis thus provide the first empirical confirmation of the importance of judicial institutionalization to the policy outputs of the post-communist constitutional courts. I also illustrate how various institutional and contextual influences, such as executive power, legislative fragmentation, economic conditions, EU accession process, the identity of the litigants, and the nature of the litigated issues, influence the activity of post-communist constitutional courts.