There are considerable biomass resources in the European Union and mature conversion technologies to exploit the potentials of bioenergy. A challenge confronting the European Union and Member States is how to accelerate the implementation of bioenergy systems and related supply chains. This chapter contributes to the identification, analysis, and discussion of constraints for bioenergy in the European Union. Adopting a combination of research methods and different informants from 6 case studies across Europe, this chapter identifies economic conditions, institutional capacity, and supply coordination as the key constraints obstructing the expansion of bioenergy. Furthermore, the case studies expose 4 points about constraints for bioenergy. First, there are no absolute constraints to realising the potentials of bioenergy in the European Union. Second, it is non-technical challenges that are hindering bioenergy rather than technical issues. Third, constraints for bioenergy are dynamic and depend on the context. Fourth, there are consistent strategies observed in the case studies to overcome constraints.