What is the role of the linguistic environment in children's early word learning? Here we provide a preliminary analysis of one child's linguistic development, using a portion of the high-density longitudinal data collected for the Human Speechome Project. We focus particularly on the development of the child's productive vocabulary from the age of 9 to 24 months and the relationship between the child's language development and the caregivers' speech. We find significant correlations between input frequencies and age of acquisition for individual words. In addition, caregivers' utterance length, type-token ratio, and proportion of single-word utterances all show significant temporal relationships with the child's development, suggesting that caregivers "tune" their utterances to the linguistic ability of the child.