The aim of this study was to test whether there is statistically significant sympathetic nervous system (SNS) synchrony between participants in couple therapy. To our knowledge, this is the first study to measure psychophysiological synchrony during therapy in a multiactor setting. The study focuses on electrodermal activity (EDA) in the second couple therapy session from 10 different cases (20 clients, 10 therapists working in pairs). The EDA concordance index was used as a measure of SNS synchrony between dyads, and synchrony was found in 85% of all the dyads. Surprisingly, co‐therapists exhibited the highest levels of synchrony, whereas couples exhibited the lowest synchrony. The client–therapist synchrony was lower than that of the co‐therapists, but higher than that of the couples. A Video Abstract is available next to the online version of this article on the JMFT web site. A Video Abstract is available next to the online version of this article on the JMFT web site.