Although the development of fairness has become a topic of wide interest, little is known about the correlates and factors that relate to the early ontogeny of fairness-related decision making in preschoolers. The current study assessed 5-year-old children’s consideration of existing inequalities in their resource allocation decisions, that is, their tendency to allocate more resources to poor others than to rich others. In addition, children’s prosocial responding toward others in pain, the amount of their social interaction experiences, and their social-cognitive abilities were assessed. The results provide evidence that children’s early social interaction experiences and empathy-based prosocial responding relate to their fairness-related decision making, supporting a relational systems approach to early prosocial and moral development.