The purpose of this study was to suggest some considerations for effective co-teaching in primary English classes. First three co-teaching models classified based on the roles of the teachers - the two teacher-centered type, the Korean teacher-centered type, and the native teacher-centered type - were discussed with the focus on the characteristics of each type. Also the other three co-teaching models based on the criteria of the division - the contents division model, the time division model, and the student division model - were discussed. Six considerations for the effective co-teaching in primary English classes sere suggested as follows. First, a Korean teacher(KT) and a native English speaking teacher(NT) need to have clear communication from planning the lesson to evaluating and reflecting on the class. Second, a curriculum for the co-teaching in primary English equation should be developed and textbooks based on the new curriculum should be developed and provided. Third, KTs and NTs need a proper training on co-teaching which helps them to work more effectively to achieve the goals of the English co-teaching. Fifth, the KT and NT need to develop mutual respect and trust to enhance the cooperation in the class. Sixth, the KT needs to communicate with the NT and students in English confidently to be a good model of communicating in English with confidence for students.