This paper argues that Mexican-American bilinguals are in danger of becoming victims of a double-deficit theory, i.e., they are erroneously considered by some to be deficient in both their languages. An article by Joseph H. Matluck and Betty J. Mace that takes the double-deficit viewpoint is refuted as being damaging to Mexican-American children. This position is defended by general remarks on standard usage, language change, interference, and first and second language acquisition; and by illustrating specific errors made in generalizing on the Mexican-American child's linguistic "deviations." (Author/AM)