This paper reviews the literature on the development of the junior high school and middle school concepts from the early 1900s to the post-World War II period. The nature of the middle school curriculum is also discussed. Meeting the needs of preadolescents appears to have been a major purpose in the establishment of the junior high school, though several factors prevented the junior high from meeting those needs successfully. The earlier maturation of each succeeding generation and renewed interest in the special character of preadolescent needs have led to demands for middle schools that can cater to younger students by providing them a place of their own and an appropriate curriculum. This curriculum caters to the social needs, demands for information about social behavior, and requirements for developing self-direction that are critical to the preadolescent. Curriculum reform efforts have taken two significantly different directions. One group of reformers argues for a return to basic, essential subject matter; another group urges acceptance of the ideas that the real curriculum is created through the day-to-day interaction among teachers and students, and that the curriculum must grow in response to the growth of the students themselves. (PGD)