Engaging with music fosters prosocial responding in infants and toddlers. In this pilot study, we examined whether music that expresses contrasting emotions (happy vs. sad) was associated with toddlers’ helpfulness. Seventy-five 18-month-olds from Hong Kong China were randomly assigned to engage with music with an experimenter in one of two conditions: happy- or sad-sounding music. After the musical engagement task, toddlers from both conditions completed the same set of helping tasks. For instrumental (action-based) helping, toddlers were significantly more helpful after engaging with happy-sounding music than with sad-sounding music. Our initial findings suggest that cues linked to happy- and sad-sounding music influence toddlers’ prosocial responses. Copyright © 2021 The Authors.