Two studies sought to identify variables that might predict relative success in student teaching performance. University supervisors ranked program graduates on overall student teaching success after they had successfully completed all mastery criteria. The first study compared students on achievement test scores, grade point average (GPA), and mastery criteria to identify differences among program graduates ranked high, middle, and low on overall student teacher success. The second study was a replication of the first, and it examined similar variables measured at several points in the program. A comparison was made of student groups ranked high and low on overall performance using the measures of GPA, the California Achievement Test (CAT), and the Performance Based Evaluation Instrument (PBEI). Although results were mixed at the secondary school level, two possible predictors appeared at the elementary school level: (1) GPA of an elementary school intern at the beginning of the program; and (2) PBEI scores at the end of the third of four student teaching quarters. A comparison of the groups on the CAT did not support this selection criterion as a predictor of teaching success. Appended tables present data on total group contrasts in all three measures and a complete data analysis of the two studies. (JD)