Over the past nine years, we have explored student conceptual understanding of physics in a wide variety of settings including universities, colleges, community colleges, and secondary schools and in courses for future physicists, engineers, and nonscience majors. We have produced activity-based materials and tools that have been used in all these settings to teach fundamental physics concepts. An important element in the success of these materials has been the use of peer learning groups. This talk will explore group work using Microcomputer-Based Laboratory (MBL) tools and curricula in the laboratory and peer group discussion as part of MBL Interactive Lecture Demonstrations. Videotaped examples will be shown and discussed. Examples of group female-male learning interactions and of different group learning styles will be shown. The effect of the nature of the task and of the group structure in the success of group work will be discussed.