The Writer's Workshop is an approach to writing instruction using a workshop model. It is being implemented in kindergarten to fourth-grade in the Houston Independent School District. The Writer's Workshop sought to improve students' writing through teacher preparation by accommodating weaker students in research-based approaches that treat writing as a process rather than a product. Teachers were exposed to four days and/or 12 hours of training in the writing process in preparation for instructing students using Writer's Workshop. Writing is seen as essential to effective communication, learning, and self-expression. The purpose of this evaluation was to determine the effects of the Writer's Workshop on teachers' preparation for writing instruction, their writing instruction, and on students' expository writing practices and performance. The effect of the workshop on students' writing performance was determined using the State of Texas Assessments of Academic Readiness (STAAR) writing scale and raw scores and the percentage of students who met the state's writing standards, a teacher survey, and classroom observations. After the evaluation, the authors recommended the following: (1) Teacher completion of the professional development designed to enhance preparation for effective delivery of the Writer's Workshop needs to be encouraged; (2) Teachers may require additional resources to effectively teach writing at the elementary school level; and (3) Future evaluations should focus on observing the delivery of the Writer's Workshop, particularly before the testing period, and possibly multiple times during the school year to assess teachers' actual writing instructional practices.