The purpose of this chapter is to present a novel knowledge management model for communities of practice to foster social innovation by leveraging on collective knowledge. We use the case of the Slow Food Movement (SFM) in Italy to analyse how collective knowledge in a population can be used by communities of practice (CoP) to enhance social innovation. The SFM is an organisation born in Italy in 1986 with the aim to promote the importance of local food heritage and traditional cooking as an alternative to fast food. As part of the remit of the SFM feature the promotion of traditional and regional cuisine, small businesses operating in short food chains, sustainable farming of plants, seeds, and the rearing of livestock that are typical of a regional ecosystem.(...) In this chapter, we propose that, although organisational capabilities play a pivotal role in determining the success of the CoP, collective knowledge gathered through market intelligence activity is a necessary social resource and input to the formation and development the CoP. We argue that collective knowledge contributes to the production of a social structure and then lead to social innovation via a mechanism of joint enterprise, mutual engagement, and showed repertoire.