Two experiments, based on the semantic differential technique, were designed to measure the tolerance level of bilingually marked English in a functional bilingual's speech. In the first experiment, marked syntactic cues were rated by different groups of judges as generally indicative of non-bilingualism, although on the whole they were not considered as impairing intelligibility. The marked syntactic cues, when isolated from morphophonemic elements, did not allow for a clear distinction between the functional bilingual and native-speakers using similar non-standard features in monoglot English. In the second experiment centering on the same subject and based on recorded speech, clear gradations were noted in the level of recognition and tolerance level of bilingually marked English. This was generally rejected as not indicative of bilingual competence by other bilinguals, by native-speaker monoglots and by learners of English, even if found to be acceptable and reasonably comprehensible. The results imply an inherent disparity between certain linguistic or widely held definitions of bilingualism that do not correlate with sociolinguistic data and the reality of some types of bilingual cases. (Author/PMJ)