A new corpus of spontaneous conversations between adults and children is examined for evidence that adults simplify their vocabulary choices when speaking with young children. If these simplifications are found to be age-dependent, then they would broaden the pattern of simplifications characteristic of ‘motherese’ to include lexical choice as well. For the age-range newborns to 12 years, the results are both consistent with and contrary to the attested set of grammatical simplifications. In this corpus, MLU and TTR are strongly age-dependent, but adults do not choose their words from the 10,000 most common word-types in English in an age-dependent manner. Rather, the additional types for school-aged children come from the same part of the vocabulary and share the same-shaped distributions as in adult speech with preschool children and infants. This absence of an age-dependent accommodation in word choice has implications for models of child lexical acquisition which assume adult language accommodation.