Co-teaching is one of the most popular models for supporting students with disabilities in general education classrooms. In spite of this, there is a paucity of research on student perceptions of co-teaching. The purpose of this qualitative study was to investigate student perceptions of co-teaching in a high school biology classroom. Over nine weeks, data was collected from students in a co-taught and traditional classroom through observations and focus groups. Qualitative content analysis identified three themes and eight categories which highlight student perceptions of co-teaching. Themes and categories that emerged were: 1) Environment which included the categories of availability of help, students feeling supported and normalcy of the classroom, 2) Instruction which included student engagement, lesson activity and teacher(s) role(s) and, 3) Relationships which included relationships between teacher(s) and student(s) and parity between teachers. Information from the study deepens researchers' and practitioners' understanding of how students perceive co-teaching and provide new avenues for future research and best practices.