Writing is recognized as a vital skill in education and the workplace; students in the United States finishing K-12 schooling are expected to be competent writers. Yet, "the Nation's Report Card" found that U.S. high school graduates coming into the workforce are particularly deficient in writing skills. Teachers serve as a crucial link in the move to improve literacy skills of K-12 students; however, teachers themselves are underprepared to be writers and writing teachers. Therefore, there is an urgent need to improve teachers' writing skills and skills of teaching writing to improve K-12 students' writing skills in the United States. This qualitative study examined the process-based writing project experienced by 22 practicing teachers through their reflective practices in a graduate capstone class. In particular, this study explored the challenges the teachers faced and the lessons they learned through the recursive phases of writing: planning, drafting, revising, editing, conferring, and publishing. The triangulation of the researchers' field notes, teachers' daily reflections, and informal interviews between the instructor and the teachers indicated that the challenges the teachers faced and the lesson they learned through the process-based writing project were phase specific. On the completion of the writing project, the participating teachers (a) developed a deep understanding of process-based writing; (b) learned new skills of planning, drafting, revising, editing, and sharing; and (c) were more confident as writers themselves and as writing teachers for their students.