Despite much research on consumers' brand identification, researchers remain divided regarding the conceptualization of the dimensions underlying social identity and how these dimensions impact marketing outcome variables. Further, previous studies have failed to examine the underlying psychological process driving this effect. The current research is the first to assess the importance of affective social identity as the mediator through which cognitive social identity impacts consumers' purchase intentions by ways of emotional and social value. Results show that affective social identity mediates the relationship between cognitive social identity and emotional value, where affect is the main driver in the formation of purchase intention. This study highlights the need to model cognitive and affective social identity separately and provides insight into how consumers' social identification influences their perceptions of identity‐linked products. Copyright © 2016 John Wiley & Sons, Ltd.