Member participation is widely considered to be the lifeblood of democratic member-owned organisations such as consumer co-operatives. However, despite this recognition of its importance, active participation is often lower than desired. In this article we first establish why this is an important issue for consumer co-operatives to address. We then present a theoretical model we call the ‘Participation Chain’, which aims to unravel some of the complexity that inheres in an important question that has, up to now, received little systematic attention - namely ‘what motivates co-operative members to participate?’. Finally, we present some research findings from a recent research project that tested the model with two types of consumer co-operative in the West Midlands region: housing and retail co-operatives. This research was conducted in partnership with the Co-operative College as part of a larger project that aimed to find new ways to create and support active ‘stakeholder members’, and therefore vivify processes of member involvement in the West Midlands.