The purpose of this dissertation was to evaluate a bilingual program using a method of longitudinal evaluation. A class of students who received instruction in grades K-2 in the Region I Bilingual Reading Project in Texas comprised the experimental group. The control group was composed of 27 older siblings of the experimental group. The control group received instruction in the traditional school curriculum. Subjects in both groups earned higher achievement scores on the posttest than on the pretest; but the experimental subjects made consistently higher scores on the five subject areas covered in the posttest. The achievement level was not significantly higher for the experimental group. The educational gain on the five subject areas was statistically higher for the experimental group with the exception of vocabulary gain. These are some of the conclusions reached: (1) subjects who received instruction in the bilingual curriculum reached achievement levels in vocabulary, comprehension, total reading, language usage and structure, and spelling that were equal to or better than the achievement levels reached by their older siblings who received instruction in the traditional school curriculum, and (2) bilingual instruction was significantly better in producing educational gain in the subject areas of comprehension, total reading, language usage and structure, and spelling. (Author/AM)