Abstract
Exploring the factors that explain the choice of governance structures in interfirm alliances, this study challenges the use of a singular emphasis on transaction costs. Such an approach erroneously treats each transaction as independent and ignores the role of interfirm trust that emerges from repeated alliances between the same partners. Comprehensive multiindustry data on alliances made between 1970 and 1989 support the importance of such trust. Although support emerged for the transaction cost claim that alliances that encompass shared research and development are likely to be equity based, there is also strong evidence that repeated alliances between two partners are less likely than other alliances to be organized using equity.