Transition studies has recently underscored the need to focus on upscaling and diffusion of innovations. A key question is how these innovations, already existing in niche markets, can become diffused and embedded in broader markets. As a first step, we offer ideas about the design and formation of what one might call ‘markets for transitions’. We argue that less attention has been paid to legitimized perceptions of market boundaries, the roles of actors, the interplay between markets, and the process character of market formation