Consumer researchers have long accepted that consumption can serve as a tool in the creation, maintenance, and expression of consumers' identities. And brands, in particular, may be important to the consumer self, even potentially serving as relationship partners. This dissertation explores how brands that are important to consumers may impact their identities at a cognitive level. Specifically, I apply Aron et al.'s (1991) "including others in the self" paradigm from interpersonal relationship research, which finds that people's cognitive representations of close others overlap the psychological self, to studying the impact of brands on the self. I provide evidence that consumers' mental representations of loved brands, which may be perceived as relationship partners, overlap the psychological self in memory. I refer to this as self-brand overlap. I also consider the relevance of disliked brands to the consumer self, providing evidence that consumers' mental representations of disliked brands are dissociated from the psychological self in memory. I refer to this as self-brand dissociation.In two studies I demonstrate and replicate the self-brand overlap and dissociation effects. And, study 2 further explores these constructs, providing evidence that self-brand overlap and dissociation are the cognitive representations of positive and negative, respectively, consumer-brand relationships. This dissertation also includes three further studies that aim to identify boundary conditions of these effects. However, no conclusive support is found for a role of any of the explored moderators. Specifically, studies 3 through 5 find the self-brand dissociation effect in every condition, in every study, suggesting that self-brand dissociation is impervious to the boundary conditions examined. Evidence for the self-brand overlap effect, which was demonstrated in both studies 1 and 2, however, is mixed in each of these 3 later studies. Potential reasons for this lack of concrete replication are offered.