The purpose of this study was to develop and test the effectiveness of a program in which activity-based science was used as a conceptual basis for language instruction. A series of four instructional units were adapted for bilingual use. Students' written and oral observations were used in experience charts and other language development activities. In this study two bilingual second grades were compared. The comparison group was taught language and science separately in a traditional manner. Both classes were tested using the California Test of Basic Skills (CTBS) language test and a criterion-referenced test of written language. Among the conclusions were: (1) Students in the treatment group made statistically significant gains in all three areas of the CTBS language test. The comparison group made significant gains in two areas, spelling and language mechanics, but not in expression. (2) On the criterion-referenced test, the treatment group exhibited higher gains than the comparison group. (3) An increase in class interaction between students of different language abilities was noted. (Author/CFM)