Within the field of writing teacher education, scholars and practitioners agree that effective writing instructors (at both the P--12 and postsecondary levels) are not simply cognizant of composition pedagogies, rhetorical theories, and their students' unique learning needs. Effective writing instructors also regularly participate--themselves--in the practice of writing. As Tom Romano (2007) explains, "Those who teach a craft ought to do a craft. When teachers of writing write, particularly in the genres they teach, they develop their insider knowledge" (p. 171). Realistically, many inservice English language arts teachers do not have an extensive amount of time to write, reflect on their writing, and translate their "insider knowledge" into pedagogical practices. One place where this type of writing-teaching reflection and development may occur, however, is in the postsecondary classroom. This article describes a graduate-level methods course, in which middle-grades and secondary-level ELA teachers completed two projects focused on analyzing, composing, and teaching an unfamiliar genre. This study extends current research regarding the use of unfamiliar genres to improve students' writing proficiencies (Bastian, 2010; Beckelhimer, 2011; Fleischer & Andrew-Vaughan, 2006, 2009) by adapting these projects to a new group of writers: inservice ELA teachers. Using a qualitative research design, this study draws upon Grossman's (1990) theoretical framework, pedagogical content knowledge, to name and define four specific ways in which the course's unfamiliar genre projects promoted teachers' "insider knowledge" as writers, thus affecting their beliefs and practices for teaching writing. (Contains 2 figures.)