What keeps an alliance leader awake during night? Past alliance research has contributed to our understanding of aspects such as motives for forming an alliance, initial conditions and the process of development. However, few studies have investigated challenges that alliance leaders face, as well as roles they adopt during the alliance life cycle. In this paper, we seek to investigate critical incidents that alliance leaders face in the execution of contract-based R&D alliances. By using the Critical Incident Technique, 158 critical incidents have been collected and analyzed. Our findings show that, in terms of frequency of occurrence, managing informal relationships and alliance formation are the two dominant themes, followed by formal R&D process, embeddedness, and exit. In addition, four crucial roles for managing an R&D alliance are also suggested. These roles are Facilitating, Finishing, Ambassadoring, and Trustkeeping. European Management Review (2009) 6, 195-205. doi:10.1057/emr.2009.16