Many mathematics classrooms use cooperative learning to support equitable learning environments for all students. Past research in the field has focused primarily on increasing achievement rather than on contexts that support equitable interactions. This year-long study in 3 secondary mathematics classes compares 2 activity structures--a group quiz and a presentation--by examining group interaction within the 2 activities. The analysis shows that groups constructed a range of work practices, including a practice focused on collaboration, one focused on individual work, and one focused on "helping." In addition, students adopted a variety of positions, including expert, novice, in-between, and facilitator. In this data corpus, experts tended to dominate interactions during group quizzes, whereas presentation preparations were more equitable, particularly when a student was positioned as a facilitator. Based on the analysis, suggestions are provided for structuring more equitable mathematics group work. (Contains 3 figures, 3 footnotes, and 3 excerpts.)