Structure as an aspect of educational setting is discussed and illustrated in the course of an argument indicating that efforts to change schools, including Project Follow Through, should aim to change structures rather than people. It is asserted that educational reform in America usually attempts to change people, especially children, and that this tendency is evident in Follow Through programs. Subsequent discussion illustrates the idea and importance of structure by describing an observational study of playgrounds. Specifically, playground structures appeared to (1) have strong, but not uniform, effects; (2) be designed into systems that can be modified but not radically changed; (3) reflect several goals and half-resolved compromises among those goals; and (4) be designed for adults as well as children. Other aspects of structure are delineated in a discussion of attempts to change the structure of a university sociology class. Concluding sections of the paper critique the mainstream of classroom research, provide suggestions for changing educational structures, and highlight three studies that illuminate the nature of school and classroom structure at the elementary level. (RH)