Over the past decade, healthcare organizations were confronted with major challenges: increased costs, greater pressure towards accountability and transparency, as well as a diminishing labor supply pool. Consequently, across the health sector, new initiatives that focus on interaction, collaboration and increased sharing of information and knowledge are taking place. Although the fragmented or distributed nature of knowledge is not specific to healthcare organizations or the healthcare sector, it seems to be particularly relevant in this setting. Healthcare organizations are professionalized institutions in which different groups with specific practices, job representations, and values converge (Tagliaventi and Mattarelli, 2006). Similarly, Van Beveren (2003) asserts that healthcare organizations could be viewed as a collection of professional specialists who contribute to the delivery of patient care. They are deliberately referred to as “collection” as often these specialists work in discrete divisions within the organization, thus fragmenting the delivery of care. This situation impacts on the ability to create, disseminate or share knowledge throughout the organizations: data are held in a number of locations, managed by a variety of people and agencies, and stored in every imaginable format (Aldred, 2002). While there has been some research on the use of boundary objects and the role of boundary spanners at group boundaries (Carlile, 2002, 2004; Star and Griesemer, 1989; Levina and Vaast, 2005; Bechky, 2003), the emergence, use, and influence of boundary objects and boundary spanners between organizations is not fully understood. This paper investigates the strategies used by boundary spanners in the healthcare sector to encourage agents from different organizational settings to join a new joint field by drawing on the concepts of boundary spanner. Using data from a qualitative field study, we argue that while some agents join the new field spontaneously, others may be reluctant to join the new joint field. Thus, boundary spanners have to find strategies to convince them to join the new joint field. Our data illustrate that boundary spanners operating in a network of organizations have to span the same boundaries than boundary spanners who operate within a single organization. However, we show how boundary spanners use various organizational and professional resources to create the new joint field. The conditions necessary for inter-organizational boundary spanners to emerge are outlined and discussed.