A bilingual prediction study was conducted in order to gather information that school districts could use in making decisions about instructional transition for students in transitional bilingual programs. In 1976, 115 third graders were tested in reading, verbal ability, and aural comprehension in both English and Spanish. Attitude toward language and school and demographic data were also recorded. The following year data were collected on English reading tests, teachers' ratings of pupil performance in five subject areas, and individual scores on an observation instrument measuring classroom participation. The data were subjected to a series of analyses that sought to identify reliable predictors of success and to determine the extent to which English proficiency alone could serve as a valid predictor. The analysis suggested that third grade reading skills in English do not offer definite predictive power with regard to classroom participation after transition. Further analyses indicated that English vocabulary skills play a strong role in prediction of success in English reading. These skills plus time-related variables are useful in predicting success in subject matter areas. The particular contribution of all variables varies according to the subject matter area concerned. (AMH)