This  paper  investigate and compare  the effect of critical thinking on educational achievement between two groups of accounting students at the Islamic Azad university and state universities. Study sample include 115 students from  state universities and 224 students from Islamic Azad university. We have used a questionnaire  to collect research data. We have also used  compare means statistical test and multiple linear regression to test research hypothesis.
Research results indicate that critical thinking impact on educational achievement. Students  with math diploma have a great critical thinking  and educational achievement score than other students. Students  at state universities have  more  critical thinking  and educational achievement score than Islamic Azad university students. Multiple linear regression also show  educational achievement  is  function of diploma type , educate at state university , gender and student's  interest.