This paper discusses the Modern School Movement (MSM), founded in 1924 by French educator Celestin Freinet (1896-1966) and widely-known throughout Europe yet largely unknown to English-speaking educators. The paper focuses on the MSM as the largest student writing network ever to have employed educational technologies as a central aspect of its day-to-day functioning. It attempts to provide a substantial introduction to the pedagogical theory behind the MSM for an English-speaking readership. It examines in detail the writings of Celestin and Elise Freinet and various MSM teachers in order to disclose the day-to-day working of interscholastic exchanges as well as a number of the major themes of Freinet's pedagogical rationale for technology-mediated correspondence networks. Following an introduction, the paper is in six sections: (1) Origins of the Modern School Movement; (2) The organization of interscholastic correspondence exchanges between MSM schools (including matching classes and forming sister class "clusters," pairing students for individual correspondence, and collective work consisting of cultural packages, group-authored letters, printed or "free" texts, and audiovisual presentations); (3) Professional development of teachers: methods vs. instruments and techniques; (4) The use of classroom technology and interscholastic exchanges to reestablish "psychic equilibrium" and to promote affective and moral development; (5) Interscholastic correspondence as a social context for literacy learning; and (6) Implications for contemporary research into computer-mediated student writing networks. (Contains 58 references.) (SR)