The NYC Leadership Academy provides coaching to principals throughout the New York City Department of Education. This presentation describes an effort to evaluate the impact of this coaching through the development and use of an online survey of principals' leadership behaviors from both the principal's and the coach's perspective. This paper describes the steps taken to develop and field-test the instrument with 520 respondents; analysis of preliminary results; and how these initial results were used to inform the coaching program. This study serves as an example of the development of a tool that can serve both formative and summative evaluation purposes, where efforts were made to involve key stakeholders and provide information that meets individual practitioner needs as well as the evaluation needs of the program. This work can also contribute to the field's understanding of the impact of principal coaching.#Non-ProfitsandFoundationsEvaluation #SurveyDevelopment #2014Conference #Prek-12EducationalEvaluation #Leadership