The social dynamic between friendship and humor has received little attention from modern researchers and is not considered in the philosophical and rhetorical literature surviving from antiquity. This study focuses on the interrelationship between friendship and humor and takes into account the intersection between these discrete fields: friendship in the ancient world, humor in antiquity, and modern friendship and humor studies.

Detailed comparisons are presented to show that our modern theories of friendship and humor are compatible with the ideas expressed by Cicero on those subjects in his Laelius De Amicitia and De Oratore. Cicero's letters are interpreted according to ancient theories and supplemented by modern theoretical advances in order to develop case studies in which the dynamic between friendship and humor is assessed.

The friendship between Cicero and Atticus is closely examined. Each element of their relationship is analyzed based on the over four hundred surviving letters written by Cicero to his dearest friend. Their friendship is confirmed, but difficulties are also identified that have the potential to erode the quality of their friendship unless resolved. The letters reveal that positive, affiliative humor is the method of choice for dealing with tensions and problems in their relationship. Cicero's use of hostile and aggressive humor with Atticus in connection with his long-term feud with Clodius is considered a model of coping humor wherein Atticus provides emotional support to Cicero as he deals with stressful circumstances.

Cicero's friendship with Papirius Paetus is tested according to the modern theory of the so-called "joking" relationship in which teasing is a central element of friendship and allows dissimilarities in values or statuses to be adjusted and stabilized. It is argued that the reciprocal teasing between Cicero and Paetus stems from a conflict in values and permits their friendship to flourish.

This study illustrates the important social functions of humor in maintaining friendship, provides new perspectives on Cicero as a friend, and explicates his use of humor.