This study explores leadership in alliances. It aims to explain how different leadership behaviors help managers to develop capabilities within the alliance team and lead to better performance. Professionals at middle and upper management levels of private and public organizations in all industries, who are/were involved in the management of alliances (inter-organizational collaboration) are asked to participate. Respondents will reflect on at least one alliance experience and give information about (a) the way the alliance was managed by the partnering organizations, (b) the leadership behaviour that was present within the alliance team, and (c) the capabilities and performance of the alliance. The results of this study will be used to create benchmarks and provide practical guidelines for those involved in managing alliances.