This paper presents aspects of the acquisition of the determiner systems of Jamaican Creole (JC) and Jamaican English (JE) used by Jamaican children from Creole-speaking communities in their first year of basic school. It shows that mixing within the Determiner Phrase of the native language—JC, with the second language—JE, is highly systematic, and suggests ways in which the language and literacy teacher may capitalize on this. Data are drawn from the Child Language Acquisition Research (CLAR) project comprising transcriptions of 214 half-hour sessions with 80 children from 13 basic schools across the island. The aim of the project was to determine what it is children speak as they enter the public school system. Findings show that the children have in their linguistic repertoires sets of forms ranging from those most like JC, to those most like JE. The choice of forms is not random, however; there are clear paterns of mixing suggesting a certain awareness of forms which belong to JE and those which belong to JC. As an example, the JE determiner ‘the’ was followed only by variants of nouns closest to JE and by no JC variants of nouns. This awareness of differences between the languages is used as a basis for supporting language awareness as a tool for increasing proficiency in English in the Jamaican language and literacy classroom.