The leadership of projects is an important area within project management domain, but the project management literature itself still tends to focus mainly on the technical aspects of project management, including planning tools and methodologies (PERT, PMBOK, Prince II etc.). For experienced project leaders, these technical capabilities are the minimum needed to be effective and the greater challenges are often presented by the socio-behavioural demands of the role. Recently, several prominent researchers with a particular interest in generating more insight into the relationship between the social and technical aspects of the project leadership challenge have been calling for more in-depth studies on the lived experience of project leaders, along the lines of the classic studies of Mintzberg (1971) and Kotter (1982) on the nature of managerial work. This research enquiry aims to investigate the lived experience of the project leader with a special focus on a particular type of project that is prevalent in practice but still largely overlooked in mainstream literature. It is referred to here as a "Loosely-Coupled Transient" (LCT) project, and it is typically characterised by multiple layers of loosely associated stakeholders, coming together for once-off projects driven by project teams comprised of diverse experts and advisors, most of whom are working together for the first and only time (such as is typically the case for many development projects in the developing world, for example). Using an exploratory, inductive approach, the research investigates the lived experience of 30 project management practitioners with substantial LCT experience, to try to deepen our empirical and conceptual insight into the nature of the leadership challenge and what it takes to be successful in this kind of project setting. The empirical findings highlight the importance of three socio-behavioural roles; context building, culture-bridging and political brokering, in addition to the more traditional technical co-ordinating role, and examines their implications for future research and practice. A novel feature of the research design is the inclusion of extra data-collection phase to allow the initial findings and their interpretation to be further validated and refined in the field.