The purpose of this exploratory case study was to examine the learning experiences of students enrolled in an all-girls and all-boys math class. Forty-nine (22 boys and 27 girls) seventh-grade students from a rural co-educational public middle school in the southeastern United States participated in the study. Seven different types of data were collected: student interviews, teacher's reflective journal, post-lesson surveys, students' reflective journals, classroom observations, student attitude surveys, and student work samples. The classroom interactions were analyzed focusing on how the two different pedagogical approaches of cooperative and competitive learning contexts shape the cognitive, psychological, and social aspects of students learning mathematics in the two single-sex classes. There were five major findings that emerged: gender differences in group cohesion, gender differences in types of motivation, different patterns of engagement, inclusion and exclusion of a group member, and stress management in individual competitions. These findings also demonstrated the emergence of gender differences in competitive groups yet not in cooperative groups. This study concludes with implications for practice, implications for research, implications for teacher education and professional development.