The George Junior Republic is described, with emphasis on its comprehensive legal-judicial system which makes it an extraordinary laboratory for the study of jurisprudence. It is a school-treatment setting for adolescents (aged 13 to 21). The educational approach is one of providing a small community modelled after the larger society—a community in which young people may have practice in a wide range of adult experiences as they perform truly necessary social and personal functions. Here the junior citizen matures through the exercise of serious responsibilities which are not entrusted to him in the usual home or school. He must help run the executive, legislative and judicial branches of his own government. He seeks jobs, is hired and fired, is paid for his work in the Junior Republic's special currency with which, in turn, he must purchase all of the necessities of life at the Junior Republic, and out of which he must save for whatever luxuries he would like to enjoy. The rotation of roles, the comprehensive overview, and the learning by participation are discussed. The Junior Republic, as a microcosm of the Society, affords a learning situation of great value to the individual. It also furnished us a laboratory for the study of the Social Systems of our society.