This thesis aims to investigate the relationships between vanity, social comparison and purchase behaviour. Specifically, this thesis defines and develops a conceptual model that expands on these relationships where vanity and social comparison act as antecedents to consumers’ self-esteem and product evaluation which in turn gives rise to purchase behaviour for luxury fashion products. Using this model, the research examines how manipulations of social comparison and vanity are reflected in these relationships and the resulting impact on purchase behaviour. To empirically test this model, an online experiment using a 3x2 between-subjects factorial design was conducted, where respondents were exposed to modified print advertisements for luxury branded sunglasses. A total of 297 responses were collected from a pool of Amazon’s Mechanical Turk workers, which were analysed using multiple regression, factorial ANCOVA and path analysis to assess the hypothesised relationships. The results indicate that vanity appeals were indeed responsible for the way in which the product was evaluated which positively translated into purchase consideration. However, though social comparison was proven to negatively impact on self-esteem, this change in self-esteem was not significant in determining purchase behaviour. Additionally, social anxiety and public self-consciousness were found to be antecedents to the modelled relationships. The theoretical and managerial implications of these findings, along with suggested directions for future research, are discussed.