The study ascertained through standardized tests, if a bilingual educational program had an effect on spoken English proficiency of native Spanish speakers in Las Cruces, New Mexico. The sample consisted of 34 fourth grade children enrolled in the Sustained Primary Program for Bilingual Students in the Las Cruces Public School System. The subjects were divided into 2 groups: group I was taught in both English and Spanish; group II was taught in English only. Taken from the same cultural and socioeconomic background, subjects were tested in a quiet room. The methods used to measure English speaking proficiency were the Ammons Quick Picture Vocabulary Test; 3 subtests of the Illinois Test of Psycholinguistic Ability taken from the representational level (Auditory Reception, Auditory Association, and Verbal Expression); and a nonverbal intelligence test (the Columbia Mental Maturity Scale). Mean scores were computed for all tests and groups were compared. To determine the significance of difference between scores, t tests were conducted on all tests. Findings were: (1) no significant differences were found between the 2 groups on English speaking proficiency in auditory reception, auditory association, verbal expression, and on the intelligence test; and (2) significant differences were found on the Ammons Quick Picture Vocabulary Test. English speaking proficiency was depressed for both groups when compared with norms for their chronological age. (Author/NQ)