The "Student Achievement Study" machine-readable data files (MRDF) (also referred to as the "IEA Six-Subject Survey") are the result of an international data collection effort during 1970-1974 by 21 designated National Centers, which had agreed to cooperate. The countries involved were: Australia, Belgium, Chile, England-Wales, Federal Republic of Germany, Finland, France, Hungary, India, Iran, Ireland, Israel, Italy, Japan, Netherlands, New Zealand, Rumania, Scotland, Sweden, Thailand, and the United States. The purpose of this survey was to get a quantitative, cross-national evaluation of educational outcomes. Surveys of student achievement were conducted in six subject areas: science, reading comprehension, literature, civics education, and French and English as foreign languages. From 8 to 19 countries participated in each survey by testing students and teachers at one or more of the following levels: 10-year-olds (Population I); 14-year-olds (Population II); and students in the last year of pre-university schooling or in programs of equivalent length (Population IV). A special sub-population was designated to include those students in Population IV who specialized in science (Population IVs). A large assortment of instruments was developed during 1966-1970 specifically for this survey. These included not only cognitive tests designed to assist student achievement in each of the six subject areas, but also background and attitude questionnaires (e.g., involving questions about home background, school experience, student attitudes, and student aspirations). Teacher questionnaires provided information on teacher background, teacher training, professional opinions, and teaching practices. A school questionnaire collected information on the organization, staffing, funding, and control for each school. The master instruments were written in English and distributed to the National Centers to be translated for local use. The data were collected in two stages between 1970-1974 and were processed between 1973-1975. Information was collected from a total of about 250,000 students, 50,000 teachers, and 10,000 schools in 21 countries. This large data bank involves 273 distinct data files and 15 codebooks (all on tape). Ten codebooks relate to merged data files about student achievement by subject area, three refer to teacher files, and two cover school data files. (WTB)