In typical development, word learning goes from slow and laborious to fast and seemingly effortless. Typically developing 2-year-olds are so skilled at learning noun categories that they seem to intuit the whole range of things in the category from hearing a single instance named – they are biased learners. This is not the case for children below the 20th percentile on productive vocabulary (late talkers). This paper looks at the individual vocabularies and word-learning biases of late- and early-talking toddlers. Experiment 1 shows that neural networks trained on the vocabularies of individual late talkers learn qualitatively different biases than those trained on early talker vocabularies. Experiment 2 confirms the novel predictions made by the simulations about word learning biases in late- vs. early-talking children. The implications for diagnosis and intervention are discussed.