This paper suggests that the institutional theory gives us a comprehensive view of basic institutional obstacles that influence the contribution Biosphere Reserves (BR) deliver to regional sustrainability. Using the four aspects of path dependence, fit, scale and interplay outlined by institutional theory as analytical axes for the analysis, the implementation and institutionalisation of six different BRs is analysed by this article. Institutional theory shows that BR models offer a way to fit in with regional characteristics while providing a cooperative tool for regional sustainability. Nevertheless, the ideas of implementing a BR not only follow bottom-up approaches with the broad involvement of local stakeholders, but also have often started from the top. The manner of their implementation has different effects on the acceptanceand perception of the BR as an institution.