Multinational enterprises (MNEs) use the regional aggregation and integration of their foreign direct investments as an important part of their internationalization. Internationalization decisions are integrated at the region level; however, little work has focused on explaining the extent of this regional integration. We develop theoretical arguments and test new hypotheses about MNEs’ general international experience and international geographic scope (i.e., institutional diversity and international dispersion) as predictors of their extent of regional integration. The results from a sample of Japanese MNEs validate these different effects, suggesting these MNE level variables are important for regional influences on their internationalization decisions. The results further our understanding of how MNEs organize their internationalization and strategic geographic foci.