This research provides a framework to achieve two objectives. First, it helps us to understand the implications of congruency of information, motivation, and perceived prestige orientation as antecedents to brand personality fit. Second, it examines the mediating role of brand image fit between brand personality fit and dilution of brand affect. The above is explained by using elaboration theory, conceptual coherence theory, and goal-derived categorization theory. The results of the implication of elaboration theory on brand personality fit were mixed. While congruency of personality dimensions between parent and extension brands has bearings towards brand personality fit, the motivation of processing information did not. In contrast to brand image fit, this study showed that the prestige orientation of a brand did not influence brand personality fit. The subsequent mediation analysis demonstrated that brand personality fit is positively related to brand image fit, but neither of these two variables has any influence on dilution of brand affect. © 2007 Wiley Periodicals, Inc.