This study examined the relationships between teacher professionalism of primary and secondary school teachers, their perceptions of trust in school principal and levels of their self-efficacy. The present study was designed in correlational research model. A total of 279 primary and secondary school teachers participated in the study. Research data was analyzed through descriptive statistics, Pearson product-moment correlation coefficients and multiple linear regression. Results indicated that there were positive and significant relationships between teacher self-efficacy, trust in school principal and teacher professionalism. Furthermore, results revealed that teachers' levels of trust and perceptions of self-efficacy were significant predictors of teacher professionalism. In the study, suggestions were made for improving teacher professionalism and following researches.