Shy children show reticence in social contexts, presumably as a way of regulating their fear. The present study evaluated whether toddler physiological regulation and parent emotion language facilitated shy toddlers’ (21–24 months) engagement with an unfamiliar female examiner. Toddler high basal respiratory sinus arrhythmia was positively associated with bold approach with the examiner. Parent emotion explanations were positively associated with toddler bold approach, particularly for toddlers with low basal respiratory sinus arrhythmia. Findings suggest that toddlers’ dispositional capacity for regulation and parents’ explanations of emotion in everyday conversations with their toddlers may help shy toddlers to socially engage.