Nowadays many firms are simultaneously engaged in multiple alliances with different partners. Alliance scholars have therefore started to develop a portfolio perspective, which analyzes the performance implications of the total collection of firms’ alliances. In this dissertation, we point to an important gap in the existing alliance portfolio literature, which has implicitly conceptualized the firm as black box by ignoring its internal structure. Instead we develop an alternative approach by framing firms as polylithic entities and acknowledging that firms often consist of different subsidiaries that each can engage in strategic alliance activities. To advance our understanding of the creation of value from alliance portfolios, this disser...