Gender differences in mathematics education have persisted in many countries despite the substantial research undertaken to understand the contributing factors and the many intervention efforts adopted to address the issue. Recent gender reformists have drawn attention to mathematical instruction as a strategy for improving girls’ learning of mathematics. In this regard co-operative learning has been consistently recommended as a strategy that has the potential to address gender equity in the mathematics classroom. While most studies have shown that co-operative learning strategies have positive effects on students’ learning of mathematics, it has also been shown that such benefits are attained when certain conditions are in place. However, the conditions under which co-operative learning can be most beneficial for all students have not yet been clearly established. Further, little is known about the feasibility of implementing a co-operative learning approach in developing countries since the bulk of research in this field has been conducted in “developed” countries. The present study was designed to investigate the above issues in a Malawian secondary school context. It was exploratory and focused on (i) the feasibility of implementing a co-operative learning approach for mathematics teaching in Malawian secondary schools, and (ii) the likely benefits of co-operative learning for students, especially girls. Data were collected in three phases. The data in phase one were collected through a questionnaire sent to 15 mathematics teachers in Zomba urban secondary schools. Phase two comprised a teacher development workshop. Main data were collected in phase three extended over a period of three months. During this period, one female mathematics teacher and 120 Form 3 (year eleven) students she was teaching in a co-educational secondary school in Zomba Urban-Malawi were investigated. The study was qualitative involving interviews and classroom observations of the students and the teacher. Data consisted of field notes, transcripts of tape recorded interviews with the students and teacher, recorded informal conversations with the students and teacher, students’ written journals and questionnaire responses of students. The results from classroom observations revealed that all students preferred co-operative learning over the traditional question/answer teaching approach because of the learning benefits it offered them. A major finding was that peer interaction significantly contributed to the students’ learning of mathematics. The peer interaction during co-operative learning activities stimulated elaboration, an awareness of knowledge gaps and inconsistent reasoning. The girls gained confidence, actively participated in discussion, showed an understanding of concepts and reported that they found mathematics less difficult as a result of their involvement in the co-operative learning approach. The findings also suggest that the question/answer approach might have contributed to the students’ negative attitude towards mathematics. The present study also highlights some of the issues that need to be carefully considered if co-operative learning were to be implemented on a larger scale and longer term in Malawi. Preliminary results gathered through the questionnaire and the teacher development workshop revealed that even though the teachers viewed co-operative learning to be beneficial for the students’ learning of mathematics (especially for girls), it was not a major part of their current instructional practice. They mostly taught mathematics using an expository teaching approach, their use of co-operative learning being limited to revising and practicing mathematics.