When does self-identity predict intention to act green? A self-completion account relying on past behaviour and majority-minority support for pro-environmental values

“Green” self-identity, that is, how much individuals view themselves as environmentalists, generally predicts pro-environmental intentions and behaviour. Factors moderating the strength of this link are, however, not clear yet. In the present paper, we examine how past green behaviour and majority/minority support for environmental values conjointly moderate the effect of an aspired-to green self-identity on pro-environmental intention. We rely on self-completion theory as an overall framework and propose that self-identity would mainly predict future action to the extent that the self is perceived as incomplete. We report four experimental studies (N = 1078) that assessed green self-identity and measured or manipulated past green versus non-green behaviour, and majority versus minority support for environmental values. Results revealed an overall positive link between self-identity and pro-environmental intention that was cancelled specifically at high levels of past green behaviour when a majority supported the participant's pro-environmental values (i.e., when the self was complete).