The concern of this paper is the problem of overcrowding in large city schools and its effect on human behavior and student achievement. It opens with a discussion of psychological and sociological research on animals that has implications for humans in overcrowded environments. Also discussed are teacher-student relationships and administrator behavior, as well as a study that shows decreased student involvement in extracurricular activities as school size increases. The paper concludes with program suggestions for small secondary schools that would increase opportunities for individualized instruction and independent study. (LD)