The aim of this study to determine the variables explaining reading literacy of Turkish students through their responds to PISA 2009 questionnaire. Variables explaining Turkish students. reading literacy were determined with items which were selected from PISA student questionnaire. The data were analyzed by using CHAID (Chi-squared Automatic Interaction Detection) analysis which is one of the algorithms of data mining decision trees. The result of the study indicated that the best defining variable of Turkish students. reading literacy is to possessions literature.