This is one of a series of reports summarizing the results of the second mathematics assessment conducted by the National Assessment of Educational Progress (NAEP). Nine, 13- and 17-year-olds were assessed during the 1977-78 school year. The assessment measured achievement in various content areas at four levels of cognitive processes (knowledge, skill, understanding, and application). This report describes performance on knowledge and skill items. The report includes results for mathematical knowledge in the areas of numbers and numeration, geometry and measurement. The results for skills are divided into computational skills (computation with whole numbers, fractions, decimals, integers, percent, and conversion between fractional form) and other mathematical skills (measurement, reading graphs and tables, geometric manipulations, algebraic manipulations and estimation skills). The report also includes group results, age level comparisons and observations on the results. The observations, consisting of interpretation, consideration of implications, and recommendations, were made by a panel of persons active in the field. It was the judgment of this panel that while performance is generally satisfactory for knowledge and whole number computational skills, achievement in many other areas is below desired levels. Among the five recommendations is that the remedy for areas in which performance is not satisfactory should not be to expand rote drill and mechanistic teaching approaches but should strive to promote understanding. (PK) Primary type of information provided by report: Results (Selective).