Purpose – User-generated content comprises an important asset for many web sites. The purpose of this study is to show how extraversion, a basic dimension of human personality, is positively related to this activity, both directly and through its impact on social identity expressiveness. Design/methodology/approach – The data come from an online survey of 1,308 online users who actively contribute content to social media. Findings – The results support hypotheses that extraversion and social identity expressiveness are positively related to active use of social media web sites, and that extraversion is related to active use both directly and indirectly through social identity expressiveness. Research limitations/implications – The findings are limited to the selection of social media to which the participants belong and provide only a partial picture of the motives behind active use of such web sites. Despite the limitations, the findings do identity two active user motivations. Practical implications – An understanding of the psychology underlying active social media use can aid managers in developing marketing strategies to encourage such use. Strategies that emphasize one's ability to express oneself freely should enhance active use, especially for the more extraverted active users. Originality/value – This is the first study to combine both extraversion with social identity expressiveness to partially explain active use of social media, thus enhancing the understanding of the motivations for active use of social media.