The Polyvagal theory proposes the Social Engagement System as a theoretical model linking social behavior with the neural regulation of the heart (via the vagus) and the striated muscles of the face and head (via special visceral efferent pathways). The current pilot study tested the feasibility of this model with typically developing 3-5-year-old children by evaluating the relation between spontaneous social engagement behavior measured by eye gaze behaviors and the visceromotor (e.g., respiratory sinus arrhythmia) and somatomotor (e.g., right tympanic membrane compliance) components of the Social Engagement System. Regression analyses supported the hypothesis that the visceromotor and somatomotor components of the Social Engagement System significantly predict social behavior (indexed by spontaneous eye gazes). Future studies assessing indices of visceral regulation and middle ear muscle function may provide insights into neural mechanisms mediating features of developmental disorders, such as autism, that have deficits in spontaneous eye gaze, auditory processing, and social behavior.