Grassroots initiatives, such as local food groups have been identified as a crucial element for a transformation toward more sustainable societies. However, relevant questions to better understand the dynamics of local food initiatives remain unanswered, in particular regarding the people involved. Who are the members in local food initiatives, what motivates individuals to get active in such groups and what keeps people engaged over the long term. This theoretical study presents a conceptual framework drawing on social psychology to describe the connection between identity processes at individual and collective levels in grassroots initiatives, such as local food groups. The framework presented is a guide for researchers in analyzing individuals' identities and their role in and across local food groups and other grassroots initiatives by recognizing identity processes of identification, verification and formation. By providing a more nuanced understanding of how individuals and individuals within groups interact in these grassroots initiatives as spaces of effective environmental action, this framework provides an in-depth perspective on the social dimension of local food systems. More specifically, by focusing on identity dynamics the framework makes a connection between the distinctive kinds of sociality and community that grassroots initiatives offer, their relevance for individuals' involvement and the opportunities to enable transformation.