Revision with unchanged content. Teachers today are faced with a myriad of responsibilities from student achievement to developing socially responsible citizens. Schools of education work on promoting teacher knowledge and skill however little has been done to advance the necessary dispositions needed to meet the diverse needs of students. Perhaps this is because few schools have been able to define what “disposition” is much less promote and evaluate the impact of disposition on teacher development or student learning. This study, conducted in collaboration with world renowned scholar Dr. Alan J. Reiman, examines pro-fessional judgment and action as key components of teacher disposition. Specifically, it addresses how mentor disposition impacts work with beginning teachers and how beginning teacher disposition impacts work with students. The book is geared toward teacher educators, those engaged in professional development, and educational researchers interested in the area of teacher disposition. It provides a concrete, measurable definition of disposition including rubrics for evaluation and explores professional development programs that can be replicated in various environments.