Description: The universal importance of reading, as one of the components of literacy was highlighted when UNESCO (United Nations Educational, Scientific and Cultural Organization) declared 1990 as the "International Year of Literacy". Therefore, one of the main purposes of education in all countries is to ensure that school students acquire the skills to read with understanding. This study was based on data from the student questionnaire and tests of the Progress In International Reading Literacy Study (PIRLS), which was undertaken under the auspices of the International Association for the Evaluation of Education Achievement (IEA). In this study we used a two stage, stratified, clustered sampling process to obtain the sample. In the first stage a representative sample of 150 (50.2%) public schools out of 299 was selected. At the second stage, one intact classroom of students in each sampled school was randomly selected. The resulting sample included 3001 students which represents 29.7% of the total population of students. The mean age of the sampled fourth graders was 9.7 at the time of testing (April, 2001). Fifty-one percent of the students were males and 49% were females. The statistical analysis used for distinguishing the factors that influence reading achievement was Structural Equation Modeling. From this analysis four factors were found to influence reading achievement. The first factor that seems to be the strongest one is related to the things happening after reading in class. Such items include the following, I write something about what I have read, I talk to other students about what I have read, I take a written quiz or test about what I have read, I do group project with other students in the class about what I have read, I act in a play or drama about what I have read, I draw pictures or do an art project about what I have read. The second most important factor is related to reading outside school. I read aloud to someone at home, I read newspapers, I read directions or instructions, I talk with my friends about what I am reading are quite a few questions related to this factor. The third factor is related to time spending to homework and the forth one on things happening during teaching.