This article examines ethnic boundary formation by analyzing how former participants in a liminal organization mobilize organizational schemas of identity and practice. I envisage Jewish summer camps as liminal organizations that provide an undifferentiated setup for immersive ethnic engagement within a clearly defined temporal period. I posit that the liminality of camp helps participants overlook the complexities of identity by transmitting organizational schemas without the constraint of structural pressures. I argue the concept of liminality makes visible structural pressures that stimulate deliberate cognition over organizational schemas. Using qualitative interviews with former camp participants, this article attends to the cognitive boundary work that underlies organizational participation. It contributes to understandings of how identity practices are shaped by institutional discourses and extends ethnic boundary theory to include liminal organizational types. I show that the structure of camp activities organizes liminality into three predominant schemas. I then show how, in the context of structural shifting, campers mobilize these schemas as salient ethnic boundaries. The results demonstrate that structural pressures encourage deliberate cognition over organizational schemas, thereby complicating projects of boundary work that structure groupness.