Intergroup bias has been a pervasive phenomenon throughout human history, but its psychological underpinnings are still the subject of debate. The present work tests whether intergroup attitudes and behaviors are motivated by ingroup positivity, outgroup negativity, or both, across the first few years of life. In two studies (total N = 128), children were introduced to an ingroup doll and an outgroup doll, and interacted with each one independently in a resource allocation task. Toddlers showed both ingroup positivity and outgroup negativity (Study 1). Preschoolers shifted from this pattern, showing positivity and avoiding negativity toward both ingroup and outgroup members (Study 2). Together, these studies suggest that outgroup negativity plays a stronger role in motivating early intergroup bias than previously thought.