The mobile phone extends the reach and immediacy of interpersonal transactions (Plant, 2000). Hence it is not surprising that personality might predict mobile phone use. We predicted that personality might predict the types of interpersonal transactions that people were prepared to engage in, and the efficacy of these transactions might have implications for self-esteem. Indeed, the present study found that disagreeable extraverts reported spending more time on their mobile phones, although they might value their incoming communications less. On the other hand, it was the extraverted, neurotic, disagreeable, and unconscientious individuals that reported spending more time writing and receiving SMS. However, there was only weak or indirect support for the expected relationships between mobile phone use and self-esteem.