For many years, researchers seemed to subscribe to the paradigm that leaders are born and not made. Seminal research, however, suggests that leadership qualities are developed over time and through professional development (PD) experiences and performance assessments (Day, Harrison, & Halpin, 2008). This paper focuses on the assessment of school principals so that the information can be used for evaluation and further PD to promote leadership behaviors. Principals, unlike teachers, are not differentiated as general or special education principals, although principal responsibilities are to oversee both general and special education programs. Researchers have not differentiated them in this regard either, so for the purposes of this paper, the authors examined research and practices that pertain to all principals who, in turn, influence teachers and all students within their schools. To advance the understanding of the assessment of principals, they identify measurable constructs that are known indicators of effective school leadership. They then present a research-based framework that describes a set of leadership behaviors that can help guide the assessment of principal performance. Finally, using this framework and standards for educational assessments, they provide a brief review of two measures of principal leadership behavior that are technically sound, aligned with professional standards, and sensitive to many aspects of effective special education programs.