International alliances enable firms to produce goods less expensively but with the same quality level, which improves their cost structure and/or helps them penetrate new markets to improve their profits. The international environments in which international alliances operate may exacerbate adverse situations or create great opportunities; in either case, their management is critical. This chapter details this unique challenge and focuses on the nature of national culture. It discusses cross-cultural management approaches and considers the alliance development framework to highlight key management issues. In an alliance, cultural differences can function as barriers to cooperation, challenges to be addressed or windows to unexpected opportunities. The active management of cultural diversity is important in alliances, and managerial attention should focus on building cultural competence, alliance manager selection, partner selection, learning and the work climate. The chapter concludes with a summary and a case illustration.