We constantly interpret and predict others’ decisions and behaviors when interacting with the world. Do our predictions of others’ decisions differ depending on whose behavior we are trying to predict? In four experiments, we probed how adults and children (N = 144, 6- to 8-years old) predict different agents’ intuitive numerical decisions. We varied the phylogenetic and ontogenetic history of the agents: an adult, a child, an infant, a chimpanzee, and an ant. We found that both adult and child participants predicted the adult and child agents to reliably choose the larger amount. Both adult and child participants predicted the infant and ant to choose at random. However, while adult participants attribute numerical decisions similar to adults and children to chimpanzees, children seem to think chimpanzees behave similarly to infants and ants. Overall, these results suggest that adults and children share similar intuitions about others’ numerical decisions based on agent identity.