Data from the National Educational Longitudinal Study of 1988 (NELS:88), which allow students to be linked to particular teachers, are used to estimate the impact of teacher degrees on student performance in the subject areas of mathematics, science, English, and history. The NELS:88 was a nationally representative survey of about 24,000 eighth graders in 1988, about 18,000 of whom were surveyed again in 1990. It was found that several teacher characteristics do appear to make a difference in student performance. Teachers certified in mathematics and those with Bachelors' or Masters' degrees in mathematics and science were associated with higher student performance scores. Mathematics and science degrees were not found to influence student outcomes in English and history, suggesting that it is the subject-specific training rather than teacher ability that results in improved performance. This finding suggests that student achievement in technical subjects can be improved by requiring in-subject teaching. (Contains 4 tables and 16 references.) (SLD)