With the expansion of the postal system from the mid seventeenth century, there was a growing interest in epistolary writing. Like real letter writers, authors of early epistolary novels focus on the material conditions of communication by letter. The most common plot devices have to do with what can go wrong in the postal system. Letter novels typically present themselves as a collection of real letters, a packet that has been lost and found, or entrusted to a friend who arranged for their publication. Epistolary fiction appealed to readers newly fascinated with how intimate thoughts could be expressed in writing, and what pleasure, as well as utility, could be drawn from reading the private thoughts of others. The letter novel was also congenial to some of the core aspirations of Enlightenment thought: a commitment to dialogical thinking, an openness to cultural difference, the notion of a ‘Republic of letters’ formed by conversational exchange between educated people who were often geographically separated. While epistolary fiction declined in popularity in the nineteenth century, letter novels have continued to resurface as experiments in narrative form, well suited to exploring contrasting subjectivities and the endless opportunities for failed and interrupted communication in the modern world.