Because child language is human language, it is important that proposed linguistic theories be able to account equally well for both child and adult speech. This paper examines a model of split-INFL, which was proposed for adult language, from the perspective of acquisition. With a focus on the acquisition of English negatives
auxiliaries, I test the ability of this model to account for the earliest observed stages of child speech in these areas. Data from several children learning English is considered and the model is found able to predict and explain the common patterns. The hierarchical structure within INFL accounts for the word order in the first
instances of negation, the relative order of appearance between negatives and auxiliaries, and the fact that the earliest auxiliaries were negated. The success in these areas suggests that a further, crosslinguistic look at the role of split-INFL in acquisition would be worthwhile.