summary: Biomass, Biovalue and Sustainability: Some Thoughts on the Definition of the Bioeconomy The success of innovation policies addressing the bioeconomy - and particularly those related to agriculture and food - will depend on how the concept is translated into policies, and therefore on how the term is understood and defined. In this article, different 'clusters' of definitions are considered, alternatively biotechnologies, biomass, and biochemical and biophysical processes as key criteria for identification. It is argued that none of these definitions properly address the issue of sustainability. In fact, a 'broad' definition of bioeconomy, encompassing all biochemical and biophysical processes, would make it useless for policy purposes. The article proposes building a definition of the bioeconomy around the concept of biovalue. It identifies the goal of the bioeconomy as the capacity to mobilise science to obtain high biovalue returns from low-cost living matter, for example organic waste, and includes the value of non-market goods associated with agriculture and food. In this regard, a distinction is made between 'natural biovalue', produced by quality agriculture, and 'biotechnological biovalue'. It is argued that the bioeconomy and the production of natural biovalue deserve specific attention and that a sustainable bioeconomy should not undermine the potential of natural biovalue through competition for the same land and water resources. ?????? 2013 The Agricultural Economics Society and the European Association of Agricultural Economists.