Current professional development efforts in writing at the secondary level have not resulted in student improvement on large-scale writing assessments. To maximize funding resources and instructional time, school leaders need a way to determine professional development content for writing teachers that aligns with specific student outcomes. The present study addressed this need by triangulating data from 3 sources to identify student-centered professional development needs for writing teachers and discrepancies between teachers' stated beliefs and actual classroom practices in writing instruction. Results revealed inconsistencies between teachers' stated beliefs and practices in terms of teaching grammar and conventions in the context of writing and providing formative feedback to students during writing instruction. Although the results of this study are specific to the focal school, experts can apply the process of collecting and analyzing multiple forms of data to determine the quality and needs of secondary writing programs in other schools.