Commissioned by the Ministry of Agriculture of the Republic of Lithuania, this report contributes to the implementation of the EUSBSR PA Bioeconomy. The aim is to illustrate how ‘Industrial Symbiosis’ (IS) can be a useful concept and model to accelerate the transition towards the green and circular economy. As point of departure this report poses the question: ‘why industrial symbiosis’? To answer it, the concept is unwrapped in connection to related concepts such as circular economy, green economy and valorisation. Furthermore, the report presents a snapshot of development of industrial symbiosis in the Baltic Sea Region (BSR), followed by more in-depth case studies in selected regions. The report, then, provides conclusions reflecting on the key factors that play a role in forging symbiotic connections between relevant stakeholders, and ends with a list of recommendations.