Part 1 of this paper reviews major research findings on the relationship of teacher characteristics to student achievement. Of the 16 teacher variables analyzed, those identified as important to student performance are teacher certification, ability and achievement, experience, inservice training, expectations for students, and methods. Policy recommendations include the development and improvement of teacher training programs in developing countries, accompanied by thorough research into the demographic, structural, and cultural context for each program and focusing on the development of teacher knowledge and ability in specific subject areas. The authors also recommend further research on the impact on learning of the unique relationships between teacher and student as well as the threshold effects of teacher competence variables. Part 2 of the paper reviews an empirical study of the effect of teacher training and teacher competence on student science achievement in the countries of Chile and India. Verbal IQ shows the strongest effect on student achievement, followed by teaching methods, teacher training and home background. (Author/WD)