The main purpose of this book is to assess the status and implementation of Cooperative learning (CL) in teaching Mathematics at high school level, Central Zone of Tigray, Ethiopia. The study attempted to explore the methods, experiences, attitude of teachers and students, factors that impede the practice of CL, its current statues and future implications. Different instruments were used to collect quantitative and qualitative data and analysed via parametric and non parametric statistical tests. Based on the findings, conclusions and recommendations were made on how to organize and implement CL so as to improve quality of education. Hence, since there has not been scientific study to explore the status and implementation of CL in teaching mathematics of the level in Tigray, Ethiopia, this monograph will be more helpful for teachers, students, and government bodies working to bring quality of education, that should be vital and becoming core issue of developing countries at this time.