This is a report on the fourth year of the Let's Be Amigos bilingual project. The project consists of three components: Model A provides bilingual/bicultural education to English-dominant and Spanish-dominant pupils in prekindergarten through fourth grade; Model B provides bilingual/bicultural education to Spanish-dominant pupils, first through third grade; Arriba provides Spanish-language instruction with English taught as a second language, grades three through twelve. Part 1 examines program processes and includes: general evaluation; curriculum reorganization and evaluation; and evaluations of Model B by principals of participating schools. Part 2 studies pupil performance and includes: pupil performance evaluation; description of standardized testing; and a study of the effect of participation in the Arriba program on graduation prevalence. Data analyses and samples of materials illustrate the report, and a bibliography is appended. (AM)