Research has shown that musical engagement promotes prosocial behavior in preschool-aged children under some conditions but not others. The current study tested whether an active musical interaction between a preschooler ( Mage: 56 months), an experimenter, and a research assistant would result in more sharing and helping behavior than a matched, non-musical interaction, while examining the extent to which a naturalistic musical interaction actually produced interpersonal movement synchrony. Verbal content was also manipulated (didactic/neutral). The results showed that musical play was associated with more spontaneous helping and overall sharing than non-musical play. Analysis of synchrony and joint movement within the experimental interaction showed that musical play resulted in significantly more joint movement and interpersonal synchrony than non-musical play, but that even in musical conditions, joint movement was only synchronized for a fraction of the length of the interaction. There was no evidence of an effect of verbal content on children’s behavior, despite uniformly high retention for the content of the song or poem across conditions. These findings provide further evidence that music making can facilitate prosocial behavior in preschoolers, regardless of lyrical content, and that joint movement may play a more significant role than precise movement synchrony in preschoolers’ musical engagement.