The act of writing is proven to enhance students' engagement in learning. At Washington State University (WSU), writing skills are identified as an instructional priority. The institution has three writing proficiency requirements for graduation: a first-year composition course, a junior writing portfolio (JWP), and two writing-in-the-major courses. Based upon the scores of JWP (n = 233), we find that our engineering students still struggle to learn the conventions and expectations for writing within the discipline-a common dilemma that other engineering programs face, too. Over the past two years, we conducted an interdisciplinary research effort to improve engineering students' writing skills in two entry-level engineering laboratory courses on engineering materials and manufacturing processes. These lab courses adjusted the view of writing instruction from a traditional modes-based approach to a rhetorical approach, an approach that has been successful in other general education courses. In practice, the course instructor and laboratory adjuncts provided a rhetorical writing review session in the beginning of the semester and graded students' lab reports to provide feedback during the one-on-one sessions. Based on the data collected from multiple years, students' writing quality and their assessment scores were found to improve. This case study of student writing in an engineering material laboratory course was conducted to study the effect of various pedagogical tools on students' lab report scores and their perspectives on writing. Data collected in student surveys and a focus group show that students found one-on-one sessions reinforced their learning from first-year composition courses, identified the expectations of the lab report as a genre, and developed their understanding of the rhetorical features of writing in the discipline of engineering.