This research scrutinizes the relationship between teachers’ perceptions of diversity management by school principals and teachers’ job performances. For this research, a relational survey model was utilized. The sample comprised 216 teachers who work in public middle school Bakırköy, İstanbul. The data were collected from teachers based on a “Diversity Management Scale” and a “Teacher Job Performance Scale”. Mean, correlation, and regression analysis were used for data analysis. Results showed that teachers’ perceptions of diversity management by school principals were at “good” levels. Teachers’ perceptions of their job performances were high in mean (x̄=4.41) in the “always” interval. Thus job performance of teachers can be interpreted as “very good”. There was a moderately statistically significant positive relationship of 46.5% between school principals’ diversity management and teachers' job performances. This suggests that teachers’ job performance increases as school principals’ diversity management grades increase. Also, school principals’ diversity management behaviors were found to affect teachers’ job performances positively by 19.8%. Therefore school principals’ diversity management could be a predictor of teachers’ job performance.