The aim of this study is to propose a social identity approach to consumer-brand affective relationships in online network-based communities by integrating social identity theory, experiential engagement and brand love literature. Specifically, this study seeks to develop a conceptual model in which social identity (SI) and social-interactive engagement (SIE) influence brand love (BL). we empirically validated the model by conducting a survey (n=387) on the facebook fan pages of 21 leading brands. The research findings support the hypothesis that social identity positively influences consumer-brand affective relationships in terms of brand love and that social identity mediates the effect of social-interactive engagement on brand love.