International diversification is a fundamental pillar of multinational corporations' (MNCs) growth strategies. Consequently, there is a considerable body of research on the performance implications of MNCs' international diversification strategies. We extend this literature by adopting a relational view where we compare the diversification profiles of firms in an inter-organizational context. We argue that the relative characteristics of firms' and their partners' diversification profiles is an indicator of parties' resource bases and thereby can explain if and when inter-organizational ties yield optimum performance outcomes. We examine these relative characteristics and propose a conceptual refinement by differentiating between the degree and content dimensions of international diversification. Analyzing data from 202 manufacturing firms from the S&P 500 list, we find that firms achieve optimum performance when their partners have moderately higher degrees of international diversification and a moderate overlap of presence in foreign markets.