I investigated associations between teachers’ interpersonal behavior, the classroom learning environment and students’ outcomes. The Questionnaire on Teacher Interaction (QTI), What Is Happening In this Class? (WIHIC), and Test Of Science-Related Attitudes (TOSRA) were used with a sample of 785 students from 75 classes in five high schools in New York. Results from the New York State Regents examination taken in June were collected for 603 students in 37 classes as a measure of achievement. Data analyses supported the factor structure, internal consistency reliability and discriminant validity of the WIHIC questionnaire and the attitude scales from TOSRA, as well as WIHIC scales’ ability to differentiate between classrooms. Data analyses also supported the internal consistency reliability of the QTI and its ability to differentiate between classrooms. Also, the circumplex nature of the QTI was supported by analyzing its pattern of scale intercorrelations. Overall, the learning environment instruments (QTI and WIHIC) and attitude instrument (TOSRA) were found to be valid and reliable when used with high school science students in New York. Simple correlation and multiple regression analyses revealed positive associations between the learning environment and students’ attitudes. All seven WIHIC scales were statistically significantly correlated with attitudes to science. Overall Teacher Support was the strongest independent predictor of student attitudes to science. Positive but weak associations were also found between learning environment and achievement (especially Task Orientation, Equity, Student Cohesiveness and Involvement). Also Equity was positively and independently associated with achievement. Associations were found between teachers’ interpersonal behavior and attitudes (Adoption of Scientific Attitudes and Enjoyment of Science Lessons) and achievement. With the student as the unit of analysis, the Adoption of Scientific Attitudes scale was significantly correlated with all the QTI scales except Strict. With the class as the unit of analysis, all the QTI scales were significantly correlated with Adoption. Leadership and Understanding were the only independent predictors of Adoption. Leadership, Understanding, Helping/Friendly, Uncertain, and Dissatisfied scales were positively and independently associated with Enjoyment of Science Lessons with the student as unit of analysis whereas, with class as unit of analysis, only Uncertain was positively and independently associated with Enjoyment. Associations were mostly in the expected directions, but with a few exceptions (e.g. Uncertain behavior was negatively related to student achievement). Commonality analyses were undertaken to investigate the unique and common contributions of the WIHIC and the QTI scales to the variance in student outcomes. The benefit of using both instruments together to predict Enjoyment, but not Adoption, was supported by the findings. Therefore, it is worthwhile to include both the WIHIC and QTI in the same study of students’ enjoyment of science. For achievement, neither the WIHIC nor the QTI accounted for much unique or common variance. A subsample of 40 students was interviewed using questions pertaining to each scale of the QTI, WIHIC and TOSRA in order to check the construct validity of the questionnaires. Findings from these interviews reinforced the validity of the WIHIC, QTI and TOSRA for use with the sample of high school biology students in New York because interview findings were mostly consistent with the means obtained for each scale. By providing validation data for the WIHIC, QTI and TOSRA, this study has provided New York teachers with instruments that can easily be used to assess associations between learning environment, teachers’ interpersonal behavior and student outcomes. Also, this research has practical implications that suggest that teachers wishing to improve their students’ attitudes and achievements should place greater emphasis on Leadership, Helping/Friendly, Understanding, and Student Responsibility/Freedom in their classroom. Also Student Cohesiveness, Teacher Support, Involvement, Cooperation and Equity should be emphasized.