This chapter describes the role of synchronization in close relationships and presents a formal model, implemented in computer simulations, that illustrates how synchronization develops in interpersonal contexts. Synchronization between individuals takes on a different and more precise meaning when viewed from the perspective of nonlinear dynamical systems. In the dynamical account, two people are synchronized to the extent that the actions, thoughts, and feelings of one person are related over time to the actions, thoughts, and feelings of the other person or persons. However, the temporal pattern of a person's phenomenal experience and overt behavior can be quite complex and hard to predict. Methods and tools have been developed to characterize temporal coordination in physical systems, those capable of highly complex and chaotic behavior. The chapter suggests that this approach, based on principles of nonlinear dynamical systems, can be adapted to the investigation of synchronization in interpersonal systems, particularly coupled logistic equations— the simplest dynamical systems capable of chaotic behavior— to investigate synchronization dynamics.