Mobile instant messaging (MIM) is one of the most influential technologies in society today due to its wide penetration in the world’s population. The present study aims to establish whether two consumer traits, extraversion and novelty seeking, have the potential to explain the intensity of MIM usage by consumers considering its good performance in explaining other consumer behaviors. The present study is based on a survey of 682 adults in Quito, the capital of Ecuador, which is a South American developing country. The data obtained are analyzed with structural equation modeling and establish that while extraversion is not related to the intensity of MIM use, novelty seeking does have a direct and positive effect. This study makes recommendations for business theory and practice.