A fi rm may maintain multiple alliance relationships that, together, constitute a fi rm’s alliance portfolio. By extending their focus beyond the management of single alliances to one that incorporates their alliance portfolios, fi rms gain additional opportunities to enhance their competitive advantage. A central issue then becomes how a fi rm can generate, confi gure and develop a high-performing alliance portfolio, as fi rm performance depends not only on the success or failure of single alliances, but also on the fi rm’s bundle of alliances. To realize portfolio synergies, fi rms must proactively design and manage the linkages and interdependencies between their partners of different alliances. However, alliance portfolios also tend to increase management complexity, coordination costs and the risk of confl icts. To be able to realize superior portfolio performance, it is important for managers to understand what an alliance portfolio is (fi rst section) and how to design and manage a highperforming alliance portfolio (second section). The next section of this chapter also provides a set of guidelines that explain how alliance portfolio management impacts the governance of single alliances. The chapter concludes with a summary and a case illustration.