This article addresses the concept of participation in the mathematics classroom, especially as it relates to students from certain ethnic and language groups and economically disadvantaged students. The authors are primarily concerned with seeking ways to develop approaches to mathematics education that are sensitive to the contexts and lived experiences of all learners. This article presents two cases located in geographically very distant settings. They share essential characteristics, however, that point to problematic areas that transcend borders, especially in reference to how certain groups of students--such as immigrants, members of specific ethnic and language groups, and economically underprivileged students--are viewed by the educational systems in place. These two cases illustrate the effects of social and organizational structures on students' participation in the mathematics classroom. [The research for the first study discussed in the paper was funded in part by The National Center for Research on Cultural Diversity and Second Language Learning through the Office of Educational Research and Improvement (OERI) of the U.S. Department of Education.]