In order to most effectively contribute to the development of solutions to society's greatest challenges, engineers must learn to lead the interdisciplinary teams required to develop these solutions. However, most undergraduate engineering programs do little to develop leadership skills in their students. Perhaps, one reason for this gap between needs and education is a conflict between the development of an engineering identity and a leadership identity. To date, the literature contains little work that illustrates the role leadership concepts play in the formation of an engineering identity. Therefore, more work is needed to understand the formation of a leadership identity within the formation of an engineering identity. Together, these development processes constitute the formation of engineering leaders. This paper presents the methods underway to validate and refine a proposed theoretical model of engineering leadership identity development. This model can be used to reshape existing engineering leadership education programs and integrate leadership into the engineering curriculum in an innovative manner. The model starts with a fundamental assumption that the engineering leadership formation process is, at its core, an identity development process. This assumption is also central to two established theoretical perspectives that informed the construction of this model. Lave and Wenger's (1991) communities of practice model argues that the development of a professional identity is the outcome of learning within a community of practice, and is frequently used to explain the process by which undergraduates develop a sense of engineering identity. The communities of practice model is then combined with Komives, Owen, Longerbeam, Mainella, and Osteen's (2005) Leadership Identity Development Model to outline how engineering students might cultivate a self-concept as a leader. A key argument within this model is that college students develop a personal sense of leadership as an identity when they view leadership as a process, not merely a position. This paper first explains the development of this theoretical model of engineering leadership identity development combining the literature from engineering identity development, leadership identity development within collegiate populations, and engineering leadership. Following this explanation, this work focuses on the methods developed and currently being deployed to validate and refine the model, including initial findings from this research.