This qualitative study investigates the identity positioning of students and teachers within one mainstream and one multilingual section of English 131 (a first-year composition course) at the University of Washington in order to examine the similarities and differences between the identity positioning of participants in each class. Following a case study approach, data included multiple interviews with four students from each section, as well as interviews with the instructors of each class, student focus group interviews following the culmination of the course, course observations, and curriculum document collection. Important similarities and differences between the mainstream and multilingual sections emerged. Similarities between the two classes largely aligned along student experiences. For example, students from both classes did not seem to position themselves as multilingual or not due to the English 131 section they chose to enroll in. Students from both classes also perceived the term 'multilingual' to mean that a multilingual English 131 class would entail increased attention to lower-order concerns (such as grammar instruction), whereas a mainstream class would focus on higher-order concerns (such as claim development). On the other hand, differences between the two classes largely aligned along teacher experiences—specifically how the two teachers identified their professional roles in the classroom and in the university. For example, the mainstream instructor positioned herself as a 'colleague' to her students, whereas the multilingual instructor positioned himself as an 'authority.' This differing positioning impacted the ways students were expected to conceptualize their roles in the classroom. However, in the instructor training that both teachers underwent prior to teaching English 131, the mainstream instructor felt herself to be positioned as a 'novice' teacher, despite the fact that she was an experienced teacher, while the multilingual instructor felt himself to be positioned as an 'expert' due to his prior teaching experience. This appeared to have an impact on the two teachers’ willingness to adopt the English 131 curriculum. Ultimately, the specifically located and enacted identities of the participating students and teachers in the two classes had complex effects as they negotiated their positioning in the classroom, amongst their peers, and within the institution.