Spontaneous speech performance of ethnically diverse subjects is investigated by measuring within- and between-group lexical interface and by assessing direction of vocabulary overlap. Interview data were collected from 144 elementary school children, comprising equal white, Chicano and black subsamples evenly divided among lower and upper grades. Analyses focus on whether texts exhibit a single lexicon better accessed by white subjects or rather generate plural lexica accessed with comparable adequacy by each ethnic group. Similar within-group lexical styles emerged. However, interface exploration found minority lexica to be different from and broader than the white lexicon they partially subsume.