The most optimal way to prepare teachers is a source of debate and inquiry. The common view held in school-based agricultural education is to use professional development to augment what teachers learned in their teacher preparation program. This has been typically implemented through induction support and generic professional development. Fessler and Christensen (1992) described a teacher career cycle that highlights the need to differentiate professional development for teachers beyond the induction stage. Teachers in the Enthusiastic and Growing stage are described as having a high level of competence, but continue to grow as professionals. The purpose of this study was to determine the characteristics of Enthusiastic and Growing school-based agriculture education teachers in order to inform professional development practice. A panel of 105 Enthusiastic and Growing teachers were selected to serve on a Delphi panel and asked to identify the characteristics of an expert agriculture teacher. Twenty-seven responses were agreed upon by the panel. Some characteristics were congruent with the existing descriptions of Enthusiastic and Growing teachers, while some descriptions were unique to school-based agricultural education. Based on these findings, professional development should be implemented using a systems approach to promote these characteristics in teachers.