Much of the discussion about the provisions on national parliaments in the Lisbon Treaty has concerned the potential for increasing politicization and parliamentarization of European Union (EU) politics. However, a more immediate change can be expected at the domestic level, as national parliaments adapt to make effective use of these new powers. In order to approach this question systematically, this article develops a framework for the analysis of the Europeanization of national parliaments that starts from the recognition that the Lisbon changes involve an inherent dynamic towards increasing transnational interaction among parliaments as well as pressures to rely more on technical expertise and administrative support in their internal workings. The processes of transnationalization and bureaucratization are considered as key indicators that help us to identify different degrees of Europeanization of national parliaments in the EU. As a final step, the article develops a typology of national parliaments based on the assumption that the more Europeanized parliaments will tend to invest more into their administrative resources and will engage to a greater extent with other national parliaments as well as with EU-level actors. The conceptual framework developed here is designed to facilitate systematic empirical research into the Europeanization of national parliaments.