Much like the organisational identification literature, recent explanations of the consumer-brand relationship can be attributed to theories of social psychology. Brand identification describes the utility of brands in fulfilling consumers' self-definitional needs. Although not a new area of research in marketing, the notion that brands can signal one's self-identity to others has .proliferated many fields of study within the discipline. The fragmentation of the field has created inconsistent and unclear conceptualisations of the construct. Furthermore, in past empirical research the construct is simply measured using established scales of organisational identification, which are argued here to be inappropriate measures of identification at the level of the brand. To address this gap in the literature, the broad aim of this thesis is to articulate brand identification as a distinct construct from that of organisational identification and to develop a scale to more accurately capture the phenomenon. To achieve this objective, it was first necessary to integrate the social psychology and branding literatures to avoid further fragmentation of the field. This synthesis provided a theoretical framework for developing an initial set of items for the brand identification scale. Subsequent studies using data from twelve samples and over 2000 subjects were conducted to refine and validate the 11 item scale of brand identification which consists of three dimensions; self-brand connection, brand signalling and brand salience. The results of the validity and reliability tests conducted on the final scale attest to its importance in marketing. Specifically, the brand identification scale was shown to have greater nomological validity than established scales of identification theory in a branding context. Further, through two quasi-experimental studies, it was demonstrated that brand identification is strongly and positively related to desirable outcomes for companies such as resilience to negative information and brand preference. Thus, the results of this thesis provide substantive implications for practitioners and academics. In particular, the findings elevate the importance of brand identification to marketing theory and show that psychological motivations for purchasing brands can be influential in predicting brand preference and choice. Further, the results suggest that practitioners need to recognise the deep, enduring relationships that consumers build with brands and should consider actively managing and facilitating this process.