A model of elementary school teacher behavior affecting pupil outcomes is presented, and research based upon that model is discussed. A portion of the model, the relationship between teacher aptitudes and knowledge, teaching behavior, and pupil outcomes is focused upon. Aptitudes considered important included verbal and reasoning ability, memory, fluency, flexibility, and sensitivity. Forty two second grade and fifty five fifth grade teachers and the pupils to whom they taught mathematics and/or reading were studied. Classroom observation, tests of student cognitive, affective, achievement, and aptitude levels, and tests of teacher aptitude, affective, and cognitive style/content tests provided a data base for analysis. Relationships between the factors tested and instructional behavior are examined. Only cognitive style and one attitude component (level of aspiration) were found consistently related over both grade levels and subject. In addition, interaction between specific teacher characteristics, especially aptitude and instructional behavior, are suggested by the data. The importance of further research to the improvement of instructional behavior, curricular change, and teacher retention is suggested. Statistical data is appended. (MJB)