Presentation of a related scientific paper (https://doi.org/10.3389/fsufs.2020.584542), made at the 5th NEST conference - May 2020 Drawing on an analysis of the Walloon dairy sector, this paper aims at bringing novel insights on the coexistence issue in agrifood transition studies. Whereas most studies explore the coexistence of farm models, our study focuses on value chains, in particular on cooperatives. In the Walloon Region, new dairy cooperatives emerged, as substitute or as complement to the incumbent vertically integrated dairy cooperatives. This paper focuses on the coexistence of dairy cooperative models as enabler of transition toward product diversification. Dairy cooperatives are hybrid actors: economic agents on the market on the one hand, structure of collective agency on the other hand. Williamson's framework of New Institutional Economics acknowledges that the allocation of resources by cooperatives depends on governance processes and on the wider institutional context in which the ...