This study examined elementary pre-service teachers' (PSTs) perceptions about norms of interaction to emphasize with fourth-grade students as they worked in teams to solve an engineering design challenge. From analysis of PSTs' lesson reflections and post-unit interviews, the findings revealed a range of PSTs' conceptions for seven social norms of interaction and indicated PSTs' emphases on norms promoting students' individual contributions versus norms encouraging collective efforts in solving the engineering problem. The results suggest focus areas for teacher educators in preparing PSTs to promote social norms for collaborative engineering design problem-solving.