The purpose of this qualitative case study was to examine how teacher collaboration influenced the participation of Leo, an ESL student, in a collaboratively taught classroom at a middle school in the Southeastern United States. To this aim, this study consisted of two collaborative cycles and used the constant comparative method to analyze the influences of teacher collaboration on Leo's participation. The findings showed that teacher collaboration generated more opportunities for Leo's increased participation. During the first cycle, Leo could focus on his own learning outcomes without assisting his friend and fellow student. Moving into the second cycle, Leo was able to confidently participate in the collaborative discussion because of the interactive lesson design and the ESL teacher's (Amanda's) impact on the collaborative process. The findings highlight the social nature of student participation that is defined by the teachers in collaboration. The findings also call for teachers' culturally responsive practices and additional studies to examine how teachers can work together to yield more equitable and inclusive spaces for student participation in the collaboratively taught classroom.