There is growing interest in the potential of grassroots innovations to play a role in the transition to sustainable production and consumption systems. However, the role of values has been little considered in relation to the development and diffusion of grassroots innovations. We develop a conceptual model of how citizens' values are mobilised by grassroots innovations, drawing on the value theory of Schwartz etal. (2012) and the theory of collective enactment of values of Chen etal. (2013). Using the results of a large scale survey of free reuse groups (e.g. Freecycle and Freegle), which enable collaborative forms of consumption, we apply the conceptual model to explore how participants' values are mobilised and expressed. We show that while the majority of free reuse group participants do hold significantly stronger self-transcendence (i.e. pro-social) values than the wider UK population, they also hold other values in common with that population and a minority actually place less emphasis on self-transcendence values. We conclude that diffusion of this particular grassroots innovation is unlikely to be simply value limited and that structural features may be more significant.