Research has shown that peer instruction in small groups can be a very effective method for students to learn deeply, develop critical thinking skills, and enhance abilities to work as team members. We have instituted a weekly small group activity into the curriculum of the General Physics courses, PHYS141 and PHYS142. The peer instruction is conducted by student Learning Assistants and the material is often interdisciplinary. We will review the literature on small group effectiveness and discuss implementation and outcomes for General Physics.