Both peer tutoring and cooperative learning are types of peer assisted learning; they involve people from similar social groupings who are not professional teachers helping each other to learn and learning themselves by teaching. Peer tutoring usually involves pairs of students, one in the role of tutor and the other as tutee, with the more able or experienced member helping the other to learn material which is new to the tutor but not to the tutee. By contrast, cooperative learning is usually done in small groups of perhaps four students, often of mixed ability. The group works toward a consensus on a problem. Because it is easier to dominate or hide in a group, roles are often assigned to each group member. Earlier perspectives tended to use the theories of Piaget and Vygotsky, perhaps with some consideration of Bandura and Dewey. Chi, King, and Graesser have been prominent in more recent work. However, a theoretical perspective is offered that integrates these elements with more practical issues. In general, both peer tutoring and cooperative learning “work”— in a wide range of curricular subjects and with a wide range of ages. Given the appropriate form of organization, cognitive gains ensue for both helpers and those who are helped. This is not the main research issue, which is exploring how and why these practices work, in order to improve effectiveness. There are several meta-analyses (a statistical procedure for combining data from multiple studies) which are relevant, and beyond this, key individual papers of specific importance are highlighted. Over the years, we have become wiser about some of the key issues. In peer tutoring, same-ability tutoring has appeared in recent years, sometimes reciprocal, and we need to know under what conditions it works. Cooperative learning has issues regarding the most effective roles for group members and how these integrate with student ability and personality. There has also been much recent work in online peer tutoring which raises different issues. The existing literature is well-developed since these are not new methods. Future research should include more tightly defined studies focusing on more minor variables of context and organization. Many teachers will say they use both peer tutoring and cooperative learning, but very often they overestimate how often anything like good practice takes place. Simply putting students together and hoping for the best will not do, although it might have mild effects. Teachers using these methods need to be clear about what organizational parameters are vital in their context with their type of peer assisted learning. These features then need to be maximized in practice and an eye must be kept on implementation fidelity throughout. Education administrators need to organize professional development for teachers which is thorough, including initial instruction and practice followed up by support and monitoring in the classroom.