The 1998 NAEP (National Assessment of Educational Progress) state level reading assessment measured fourth- and eighth-grade students' reading proficiency in situations that involved reading for three purposes: reading for literary experience, reading to gain information, and reading to perform a task (grade 8 only). This report describes the reading proficiency of Illinois fourth-grade nonpublic school students and compares their overall performance to students in the Central region of the United States and the nation (using data from the NAEP national assessments). Illinois participated in the NAEP reading assessment for the first time in 1998. Public schools at grades 4 and 8 and nonpublic schools at grade 8 failed to meet minimum participation guidelines for reporting. The average reading proficiency of fourth-grade nonpublic school students in Illinois on the NAEP reading scale was 237 compared to 233 nationwide. (RS)