This thesis examines how the core messages of UNESCO's Man and the Biosphere (MAB) programme and their transmission and interpretation among the programme's different participants and stakeholders have evolved from the programme's inception in the late 1960s to the present day, and provides recommendations on how to strengthen MAB's current communication practices. Initially established as an interdisciplinary programme comprising 14 distinct research projects investigating the relationship between humankind and the biosphere with the objective of generating the knowledge and wisdom to improve it, the approaches and methodologies advocated by MAB have changed considerably over the past decades. MAB is today best known for its global network of 669 biosphere reserves at which the methodologies and concepts advocated by the programme are trialed in practice. Through a historical analysis and three case studies examining the implementation of the MAB programme in Vietnam, Palau and Australia, respectively, the trajectory of MAB's messages and their interpretation are examined in detail. The research undertaken traces a number of significant shifts in the way new knowledge and practice is generated within MAB, from its origin as a research agenda produced by a gathering of elite scientists to a decentralized network of experimental sites at which new approaches towards sustainable development are put into practice in accordance with local priorities. The three case studies demonstrate how MAB's basic concepts and ideas are increasingly interpreted based on local conditions and priorities, sometimes approaching self-organization occurring in relative isolation from either the national or global levels of the programme. The research also shows that MAB's wide-reaching research-derived objectives have made the articulation of a clear and coherent definition of the programme's core purpose difficult, posing a challenge to the programme's national coordinators and biosphere reserve managers charged with the responsibility of implementing MAB in-situ. In conclusion, a series of recommendations addressed to MAB's governing bodies are made on the basis of the analysis performed, advocating the establishment of a global frame of reference within which to communicate MAB's original open-ended and inquiry-based objectives, thereby allowing biosphere reserves to develop locally appropriate and specific interpretations of the programme's objectives; the articulation of a more precise definition of the biosphere reserve's purpose; the elaboration of more targeted communications with the individual biosphere reserves; and the development of accessible guidance on the implementation of the programme in practice.