Purpose: The transformational leadership paradigm has been a focal point in organizational research, but a critical methodological question remains: whose perception of transformational leadership should be relied upon for accurate evaluation? This study addresses this question by examining the differences that arise depending on whether the leader’s or their followers' assessment of the leader's transformational leadership is used. Methodology: Transformational leadership behavior (TLB) perception data were collected from both leaders (n=372) and their followers (n=892) to analyze its impact on organizational commitment (OC) and organizational performance (OP). Structural equation modeling was employed to reveal the impact of TLB on OP from both leader and follower perspectives. Findings: Both leader and follower perception models exhibit a significant positive effect of TLB on OP. However, the mechanisms differ substantially. In the follower perception model, the impact of TLB on OP is almost entirely mediated through OC. Conversely, in the leader perception model, the impact of TLB on OP is split between the direct effect of TLB on OP and the mediated effect through OC on OP. Unique Contribution to Theory, Practice, and Policy: These findings have significant implications for interpreting past research on transformational leadership and future methodologies. The study contributes to the literature by offering a comprehensive understanding of the relationships between TLB, OC, and OP, particularly in the public sector, utilizing a large-scale sample.