How can global team leaders effectively span boundaries between highly diverse and distant team members, manage cross-cultural conflict, and foster team performance? Global team leadership continues to face persistent challenges, and while the boundary spanning literature has identified relevant characteristics, traits, competencies, and skills of effective boundary spanners, it says little about boundary spanning activities. This paper proposes new contributions to this question through an ethnographic case study of a highly successful global R&D project team. Over the course of the 2-year project, three conflict situations were resolved through cross-cultural boundary spanning activities. From an ethnographic perspective, the dynamics at work are described in detail. To better understand these dynamics, the paper draws on loosely coupled systems theory by asking how structural and cultural coupling can facilitate boundary spanning activities. In doing so, the paper extends the theory of boundary spanning and global team leadership and connects boundary spanning with loosely coupled systems theory. The contributions relate to four main propositions: effective global team leaders span intra-team boundaries through coupling activities; task-related “structural coupling” and relationship-related “cultural coupling” are interdependent; effective boundary spanning combines tight structural and loose cultural coupling; and boundary spanning objects and agents enhance coupling activities.