Previous research has demonstrated that people's movements can become unintentionally coordinated during interpersonal interaction. The current study sought to uncover the degree to which visual and verbal (conversation) interaction constrains and organizes the rhythmic limb movements of coactors. Two experiments were conducted in which pairs of participants completed an interpersonal puzzle task while swinging handheld pendulums with instructions that minimized intentional coordination but facilitated either visual or verbal interaction. Cross-spectral analysis revealed a higher degree of coordination for conditions in which the pairs were visually coupled. In contrast, verbal interaction alone was not found to provide a sufficient medium for unintentional coordination to occur, nor did it enhance the unintentional coordination that emerged during visual interaction. The results raise questions concerning differences between visual and verbal informational linkages during interaction and how these differences may affect interpersonal movement production and its coordination.