Social media platforms are a significant growth opportunity for enterprises, especially for microenterprises, due to the possibility of establishing direct contact with their customers. We investigate the psychological reasons that drive entrepreneurs towards the use of social networking sites (SNSs) for their business, following two important social psychology theories: the theory of planned behaviour and the technology acceptance model. We also tested for two personality traits: openness to experience and dominance. Data were acquired by examining 325 microentrepreneurs who decided to use either SNSs or traditional sales methods for their businesses. Our results confirm that of all the behavioural antecedents tested, perceived usefulness and attitude towards SNSs’ effect on business proved to be the best predictors of the intention to use (or continue using) SNSs for business activity. Implications and suggestions for future research are also discussed.