This article presents the various definitions of co-teaching as well as its rationale and the elements necessary for co-teaching teams to work effectively. The most generally accepted models for co-teaching are described. The benefits of co-teaching to both students and teachers are discussed. Research-based expressed needs of co-teachers are presented. Common barriers to co-teaching are described with suggested strategies for overcoming such barriers. Finally, an extensive review of the most up-to-date research on co-teaching is provided followed by a linking of co-teaching to national teacher standards. Co-teaching websites and further readings are recommended.