The correlation between a bilingual's usage of grammatical morphemes from one of his/her languages and his/her language dominance is examined. The subject is a three-year-old Danish/English bilingual who code-switches at the morpheme level even though she has never been exposed to a code-switching bilingual community. Co-occurrence restrictions are found in her code-switching grammar as follows: English grammatical morphemes co-occur with either English or Danish lexical morphemes, but Danish grammatical morphemes co-occur only with Danish lexical morphemes. It appears that in utterances containing morpheme-level code-switching, the encoding of grammatical morphemes in one language is an indication of the dominance of that language. By that criterion, the code-switching of this subject is English-dominant. (Author/MSE)