Students who are engaged writers are likely to produce better writing and to enjoy writing more than students who are disengaged writers. Yet, we are unaware of any existing tool that validly and reliably measures writing engagement. In this article, we describe what writing engagement is and why it is important. Then, we present the Writing Engagement Scale, a valid and reliable tool for measuring writing engagement, and outline how teachers can use this tool to better inform writing instruction in their classrooms.