This essay, written from the point of view of a social researcher with a direct personal involvement in the cases studied, discusses how public schools, as universally accessible moral communities, engage in patterns of systematic exclusion. Through three case studies of public secondary schools in which groups of students have been situated outside the schools' boundaries, this theoretical analysis considers educational ideologies of "merit,""choice," and "tradition" as they have justified moral exclusion. The following schools were involved in the case studies: (1) Comprehensive High School (New York, New York); (2) Dwight Morrow High School (Englewood, New Jersey); and (3) Central High School (Philadelphia, Pennsylvania). The following aspects of each case study are discussed: (1) school characteristics; (2) the exclusion issue; (3) the ideologies used to cover up the exclusion practices; (4) the researcher's role in resolving each exclusion problem; and (5) the decisions concerning the exclusion problem. Across the schools, students were being educated within publicly sanctioned communities of exclusion, sheltered from a rich education of diversity and critique. The analysis contained in this essay challenges scholars and practitioners interested in public education to probe beneath the surface of ostensibly neutral ideologies, and to expose the dynamics of moral exclusion shadowed by some liberal arguments voiced ostensibly for the "common good." A list of 20 references is included. (JS)