Social Networking Sites (SNS) are gaining momentum as powerful tools of marketing communications. Mobile phones are becoming one of the most popular devices for accessing Social Networking Sites. In Spain, 44% of Social Networking Sites users access these sites on a daily basis while 79% of them access these sites on a weekly basis. Furthermore, it is notable that over 70% of Social Networking Sites users talk about and recommend commercial brands. This justifies the interest of the study of Social Networking Sites users from a marketing perspective. The aim of this research is to assess the influence of consumers` personal factors (attitude, innovativeness, and gender) and individual-media relationships (media affinity and individual-media dependency) on mobile SNSs usage behaviour. Managerial implications improving marketers´ advertising effectiveness are also provided.