Problem Statement: Teacher leadership has recently attracted the attention of scholars and practitioners due to its promotion of student learning and school improvement. Thus, there is a need for investigating the construct of teacher leadership and its relationship with various organizational and personal variables. Considering the fact that research on teacher leadership is scarce, the present study may serve as an important data source for policy makers in regard to developing high-quality teaching and learning in schools. Purpose of the Study: This study sought to examine the relationships between teacher leadership, teacher professionalism, and perceived stress. Teacher leadership was the dependent variable of the study, whereas teacher professionalism and perceived stress were the independent variables. Method: The present study employed a correlational research model where two independent variables and one dependent variable were used. A total of 302 teachers participated in the study. The Teacher Leadership Scale, Teacher Professionalism Scale, and Perceived Stress Scale were used to gather data. Descriptive statistics, Pearson's product-moment correlation coefficients, and a step-wise multiple-regression analysis were used to analyze the data. Findings: Results indicated that there were positive and significant relationships between teacher professionalism and dimensions of teacher leadership, such as institutional improvement (r = 0.35, p < 0.01), professional improvement (r = 0.36, p < 0.01), and collaboration among colleagues (r = 0.20, p < 0.01). However, there were negative and significant relationships between perceived stress and dimensions of teacher leadership, such as institutional improvement (r = -0.28, p < 0.01), professional improvement (r = -0.35, p < 0.01), collaboration among colleagues (r = -0.30, p < 0.01), and teacher professionalism (r = -0.21, p < 0.01). Professionalism and perceived stress together explained 16% of the total variance in the institutional-improvement dimension, 21% in the professional-improvement dimension, and 11% in the collaboration among colleagues dimension. Conclusion and Recommendations: Results confirmed that teacher professionalism and perceived stress were important variables predicting teacher leadership. In this regard, an organizational structure supporting the professional behaviors of teachers and minimizing the factors causing them to experience stress should be created, and a school's organizational structure should be supported by a healthy organizational climate to promote teacher leadership.