Over the last two decades, strategy researchers have sought to understand the ownership structure of firms' foreign direct investments (FDI) as reflected in entry mode and equity level. However, prior FDI research has ignored the interrelated nature of these key FDI decisions. In addition, prior research does not fully account for the fact that individual ownership structure decisions occur within the context of a firm's broader FDI portfolio, and thus reflect a wide and frequently unobserved range of parent firm and host nation effects. Our research seeks to address both of these limitations. Using a rich dataset of 4,459 subsidiaries established by 858 Japanese firms across 38 countries over a 9-year period, we specify a conditional bivariate, cross-classified multilevel model of FDI ownership structure. Our model enables the joint estimation of entry mode and equity level, accounts for the portfolio nature of FDI, and compares the relative predictive power of transaction cost- and experience-based explanatory variables across both facets of ownership structure. Copyright © 2007 John Wiley & Sons, Ltd.