Descriptions of curriculum often divide it into components entitled intended, implemented, and learned. Each domain intersects with the next to form a sequence of events in which curriculum, teacher, and students are major participants in the process of curriculum modulation. The focus of the research reported in this paper was to study the learned curriculum which is defined as the sum of student's learning in the areas of concepts, skills, attitudes, cognitive abilities, and understanding the nature of science. During the course of the study within a Department of Defense Dependents School on a military base outside the continental United States, the objectives were extended to explore the phenomenon of the hidden or unintended curriculum and to define, clarify, and interpret its presence, possible causes, and effects within the student culture of the chemistry classroom. The results from this study indicate that the social order created by the students represented their adaptations to educational circumstances, both local and institutional, and the consequences of the unintended curriculum influenced social and personal values and attitudes. To minimize the effects of undesirable, unintended consequences of the hidden curriculum educators must continue to examine the social construction of knowledge and the meaning that various experiences have for individuals, determine causes, and retailor classroom interactions accordingly. (Contains 25 references.) (JRH)