This article describes the use of a progressive paper in a capstone course to develop students' writing skills. A progressive paper is one that students write one section at a time: as they add each new section, they go back and revise the previous parts based on actionable feedback from the instructor. In this course, the progressive paper takes the form of a laboratory report for a multistep synthesis. Students revise and update this paper throughout the semester. Each revision coincides with an additional step in the synthesis. This results in a complete journal-style article at the end of the semester. The students in this course show significant improvement in their writing skills throughout this process.