An analysis of the language backgrounds of 237 persons in a psychology department subject pool is presented. Specific findings indicate that (a) only about two-thirds of the subjects were native speakers of English, (b) native English speakers can be divided into several different groups on the basis of bilingual background and age of acquisition of their second language, (c) the number of native English speakers who would be considered ideal for psycholinguistic experiments in English (e.g., monolinguals and bilinguals who acquired a second language in or after adolescence) is only about a third of the sample, (d) nonnative English speakers appear to have their native, non-English-language abilities reduced as a function of their acquisition of English; that is, English appears to displace other languages that a person knows (the English displacement effect), and (e) age of English acquisition is shown to be an important factor, by correlating negatively with rated English abilities and reported Scholastic Aptitude Test (SAT) scores, and positively with rated ability in a non-English language.