The facial behavior of patients and therapists provides a valuable window into the therapeutic process, especially with regard to the alliance. Contributions come from the behaviors of each person as well as their level of interpersonal synchrony. However, contrary to extant theories, the associations of synchrony with working alliance and outcomes depend on the behavior being synchronized, the informant providing ratings, and the level of analysis being conducted. (PsycInfo Database Record (c) 2025 APA, all rights reserved).