The scholastic achievement and demographic characteristics of more than 20,000 homeschool students were assessed by Dr. Lawrence M. Rudner, director of the Educational Resources Information Center Clearinghouse on Assessment and Evaluation at the University of Maryland. All the students took the same national, norm-referenced tests - the Iowa Test of Basic Skills (ITBS) for grades K-8, and the Tests of Achievement and Proficiency (TAP) for grades 9-12. The ITBS is used nationwide in many public and private schools.

Participating families agreed to be evaluated before their children's test scores were known, thereby reducing the "self-selection bias" factor that is often criticized in homeschool studies.

Other major findings include:

Nearly a quarter of homeschool students are one or more grade levels ahead of their peers in public and private schools;

Students who have always been homeschooled have higher test scores than those who have attended public or private schools;

There was no difference in achievement among students whose parents had teaching credentials compared with those who did not. However, significant achievement differences were found among homeschooled students when classified by the amount of money parents invested in homeschooling or their level of education.

Author Rudner, who said in an appearance on C-Span that he is "personally a big supporter of the public schools," claims the study does not prove homeschooling is superior and should not be taken as criticism of public or private schools. He emphasizes that his research "simply shows that homeschooling works for those who make the commitment."