Previous literature has found a significantly positive relationship between green lifestyles and subjective well-being. These well-being gains could either come from individuals’ conformity with a general social greenness norm or from adhering to a group-specific norm that enhances individuals’ sense of identity. We aim to provide a better understanding about those two channels. We construct measures of the regional prevalence and diversity of green self-image as indicators of the strength of a hypothetical green social norm. Using panel data from the UK, we find the positive relationship between individuals’ green self-image and life satisfaction to be unrelated to the prevalence of greenness attitudes, whereas the more polarized green/non-green attitudes are, the more well-being is gained from being green and the less well-being is lost from being non-green. This evidence is consistent with the idea that the relationship between a green lifestyle and subjective well-being relies (in addition to conformity with an internalized moral norm) on group identity more than on conformity with a society-wide green norm.