An analysis of how members of a bilingual sixth grade classroom construct knowledge as they interact within a particular event of a social science history project is presented. The analysis shows how theory informs practice and how practice informs theory. Data are presented to illustrate ways in which knowledge is constructed by members through interaction in a local event and over time. Ways in which positions and positionings are established by bilingual and Spanish or English dominant students through their actions are discussed along with related issues of language use.