The transition to a circular economy relies on systems that facilitate waste recovery and recirculation of resources. These systems are based on certain enabling technologies. The aim of this paper is to explain how socio-economic structures influence the diffusion of such technologies. It applies a framework built on societal embedding and varieties of capitalism to compare the diffusion of anaerobic digestion (AD) in Sweden in northern Europe and Paraná in southern Brazil. Both Sweden and Paraná have experienced accelerated diffusion of AD, but there are significant differences in the respective diffusion patterns. The comparative analysis points to a tradeoff between system complexity and speed of diffusion. It illustrates how AD can be presented as a solution to various problems, and it further shows how the specific problems that gain attention shape diffusion patterns. By showing how socio-economic structures influence the appointment of problem owners, their agency, and legitimate forms of institutional support, the analysis demonstrates how economic systems condition technology diffusion. © 2021 The Authors