The purpose of this study was to analyze the impact of writing on the content areas when coupled with ongoing professional development and support for content-area teachers. Research shows that writing is an essential skill for success in and beyond the school setting. Research further indicates that writing plays an important role in student learning through its development of cognitive processes; however, in general, writing as a mode of learning is not a focus of either pre- or in-service teacher training. As such, writing beyond note-taking and fill-in-the-blank activities is not necessarily a strategy utilized in content-area teacher classrooms. This dissertation analyzed the impact of writing professional development and implementation on content-area student achievement in both content-area knowledge and writing skill. Data were collected through a survey instrument, pre- and post-assessments, benchmark assessments, and teacher reflection questionnaires for qualitative and quantitative results. Teacher participants were employees at a rural public charter high school in North Carolina. Student participants were high school students enrolled in participating teacher content-area courses. Per analysis of the data, it was determined that writing professional development and implementation impacted student achievement in both content-area knowledge and writing. In addition, the results indicated that both student and teacher attitudes toward writing as a mode of learning were positively affected. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]