The "PESO" Bilingual Language Development Project was a 1-year pilot study in 4 West Texas county school districts involving 451 Anglo and Mexican American 1st- and 2nd-grade students. The project contained 3 components: (1) the development of bilingual oral and written language skills--instruction in the Spanish language, and the concomitant development of concept formation ability, self-image, and cultural awareness; and instruction in English, within the regular school program, (2) the development of a well-trained staff of bilingual teachers, and (3) through parent involvement, the development of a positive relationship between the school and community concerning the bilingual program. The objectives of the instructional component were achieved to a significant level; however, the attempt to develop Spanish written language skills failed. Testing indicated the need for an entire year to develop Spanish oral language skills. Staff development and parent involvement objectives were met. Procedures for the attainment of these objectives were deemed practical, but the evaluation design was thought to need further development owing to the lack of adequate measurement devices in Spanish language development. Eight exhibits, including a parent attitude survey and evaluation reports, and 12 tables of test results are appended. (MJB)