Windowless school buildings are currently being proposed as a design solution to the problems of vandalism, energy conservation, and building costs. However, little consideration is being given to the effects of windowless classrooms on the students and teachers inside. This thesis describes the effect of windowless classrooms on three specific areas of cognitive behavior: rote learning, concept formation, and perceptual ability. In addition, a description of student and teacher affective behavior, based on formal observations, is included. Two identical sixth-grade classes were selected for the study. The experimental period was divided into two three-week phases. Each classroom had all existing windows covered during one phase. Students were randomly divided into three test groups for the testing phases of the study. No consistent trends emerged to allow definitive judgment that windowless classrooms are detrimental to student cognition and learning. The only definitive trend is in the realm of affective behavior, indicating that student aggression increases in windowless environment. (Author/MLF)