Music plays a significant role in human life. It is a form of art and entertainment and a powerful medium for interpersonal interaction. The experience of listening to music is often emotional. Previous research has elucidated many of the mechanisms that effect an emotional response in the listener. In contrast, much less is known about how joint musical engagement impacts emotions. Here we focus on synchronized rhythmic interaction, a fundamental feature of musical engagement. There are theoretical reasons for hypothesizing that synchronized interaction should elicit positive affect among interacting individuals, although empirical studies performed with adults have found little consistent evidence for such an effect. We revisited this question, studying children instead of adults, and used an implicit measure of experienced affect to compare children's responses to synchronized versus asynchronized joint tapping. Unlike previous studies, we distinguished between musically trained and untrained participants, because a background of musical training may be associated with altered emotional sensitivities to rhythmic interaction. We found a striking difference in emotional responses to synchronized versus asynchronized tapping, which strongly depended on musical training background. The untrained children responded to synchrony with more positive affect and less negative affect when compared to asynchrony, in line with theoretical predictions. In contrast, the musically trained children showed low positive affect following both synchrony and asynchrony and more negative affect in response to synchrony rather than asynchrony. These results suggest a possible emotional dissociation between synchronized and asynchronized interpersonal rhythmic interaction that may be influenced by musical training background. (PsycINFO Database Record (c) 2019 APA, all rights reserved).