Intended to enable Catholic educators to evaluate and compare the writing progress of their students to that of the nation as a whole, this report presents writing achievement data of Catholic school students in grades 4, 8, and 11, assessed in 1983-84 by the National Assessment of Educational Progress (NAEP). A summary of the findings of the NAEP Reading Report, a complementary study, is presented and discussed in terms of a larger school-based context. The first of three sections reporting NAEP writing results presents comparisons based on the following factors in student' background: demographic characteristics, parental education, and residential location. The second section provides overall score comparisons, while the third section analyzes the writing proficiency scores in terms of grade level, school grouping, and racial/ethnic group. The major findings derived from these comparisons indicate that (1) writing scores in both types of schools are not very high, on average; (2) Catholic school students write better than the national average at all three grade levels; (3) students gain more writing skills in late elementary and middle school than they seem to during secondary school; (4) on average, girls are considerably better writers than boys in both types of schools and across all grade levels; and (5) minority students (Black and Hispanic) score considerably below White students in writing in both type of schools. (JD)