The data presented in this paper were collected from 73 early childhood, elementary, and middle school teachers who were among the first teachers to prepare for formal mentor teacher leadership roles in Massachusetts. These teachers were enrolled in a graduate mentor teacher preparation course at Wheelock College (Massachusetts). The Inventory is divided into two major sections. Section 1 includes five categories of information that reflect the topics addressed in the mentor preparation course: Personal Motivation for Becoming a Mentor; Personal Traits and Qualities; Areas of Knowledge and Skill as a Classroom Teacher; Areas of Knowledge and Skill as a Mentor Teacher; and Knowledge of Organizational Issues. Section 2 of the inventory helps teachers formulate individual action plans to address the areas of need indicated in Section 1. The findings indicate that teachers are motivated to prepare for new formal mentor teacher roles primarily because they seek an avenue for their own professional growth and stimulation; helping novice teachers is a secondary motivating factor. In addition, this research indicates that most of the aspiring mentor teachers want, but after several years of successful teaching do not possess, the knowledge and skills to create and/or assume new teacher leadership roles. Implications of the study are discussed and a new master's degree which includes a Teacher as Leader program is described briefly. The appendixes contain the inventories used for data collection. (IAH)