According to Margaret Gilbert, a joint commitment (JC) is a commitment of two or more agents, called the parties of the JC, to engage in a common project. Creating a JC often involves an explicit agreement, carried out in a conversational interaction through overt communication. We explored aspects of such interactions that can be considered as complementary to verbal exchanges, focusing on how a JC is managed by the parties by means of emotional and other non-verbal bodily expressions. We analyzed three phases of the JC lifecycle (creation, maintenance, and violation), and in particular the emotional reaction of the participants to two types of violations by the experimenter. In our analysis we used standardized tools such as the Ethological Coding System for Interviews, the Mind Reading Emotional Library, and the Facial Action Coding System. Our results show that certain non-verbal behaviors in the phase of JC creation are characteristic of the participants who later did not fulfill their commitment. Moreover, the participants' emotional reactions to JC violation by the experimenter turned out to depend on the type of violation. Finally, the creation and maintenance of JC, and the emotional reaction to its violation, appear to be independent of the participants' personality and empathic disposition.