This article provides a conceptual basis for a teacher preparation course designed to improve the writing skills and teaching practices of in-service teachers. To propose this course, we first examined the research on preparing all secondary in-service teachers to use writing well. Research suggests that teachers' histories as writers greatly affect whether they feel confident enough to use writing with their students. Even though many teachers believe in the value of using writing for instructional purposes, they report significant challengesnamely, a lack of professional preparation and time. Given our experiences as graduate faculty members in a large university, we discuss the need for the graduate-level course that we developed. The curricular design is described, and student survey results suggest that the course is effective. Implications for in-service teacher preparation and professional development are presented in light of recent calls for writing reform.As a response to the need for improving the state of writing in secondary schools and for improving teacher training in the area of writing, we provide the background and framework for a research-based course designed to prepare in-service teachers to meet the challenges of writing across all secondary content areas. Years of experience have taught us that many content-area educators do not feel well prepared to teach writing. Oftentimes, they lack the confidence to use writing with their secondary students. Not surprisingly, the teacher educators and professional development professionals who work with these teachers have many questions regarding how to support these in-service teachers-namely, Why does writing matter?What is the state of writing in schools today? What challenges do teachers report when they attempt to use writing in their classrooms?Is there a research-based model of professional development that could serve as a model for supporting in-service writing teachers?Because these questions are important, genuine, and common among teacher educators and professional development facilitators, they deserve legitimate and well-researched responses. Although we originally asked these 38 CHRIS STREET AND KRISTIN STANG questions because we wished to improve our own practice as teacher educators, we hope that the answers will enlighten teacher educators who strive to improve the writing skills and writing pedagogy of in-service teachers.