“In This Together: Consubstantial Ethos in Writing in the Sciences Classrooms” explores the ethos of instructors tasked with instructing STEM students how to write in the sciences. Building on the importance of ethos in education and Dale Sullivan’s foregrounding of the importance of consubstantial ethos in building effective communicative acts, this study sought to determine how student and instructor perceptions of ethos were similar and dissimilar to determine if there was a sense that we were truly “in this together” as Sullivan claims is necessary. For this mixed-methods study, I distributed surveys to students as they entered and exited the course. Student surveys inquired about attitudes and beliefs about previous English courses, the trajectory of the course, the overall worth of English courses, and their roles within the course. Instructor surveys, in turn, asked mirrored questions to see how instructors perceived students’ attitudes and beliefs towards the course, the practice of writing, and WAC/WID and English courses more broadly. Encouragingly, the majority of students reported seeing a value to English courses, but this worth was primarily seen as emerging from two components: 1) the content of the course and 2) student perceptions of the instructor—both, this project argues, are closely tied to ethos. As such, the final two chapters of the project suggest adjustments to foster optimal ethos for Writing in the Sciences courses by introducing more direct teaching of Writing Studies theory in such courses and implementing assignments such as the Forum Analysis and Popular Discourse Report that encourage students to critically analyze the work of experts writing in their fields.