The National Assessment of Educational Progress (NAEP) is an information-gathering project that surveys the educational attainments of 9 year olds, 13 year olds, 17 year olds, and adults (ages 26 to 35) in ten learning areas, one of which is writing. This report focuses on persuasive and explanatory letter writing, representing two basic aims of discourse. The letters, divided into two broad categories of social letters and business letters, were read and categorized by experienced English and composition teachers. NAEP reports the responses to certain exercises of groups of individuals defined according to sex, race, region of the country, level of parental education, and size and type of community. Some of the report's observations are that simple explanatory-writing skills are developed sometime between the ages of 9 and 13 and that persuasive-writing skills are complex and difficult to master. (JM) Primary type of information provided by report: Results (Selective).