Critical Thinking has accompanied man since his creation. Man steps toward Critical Thinking when he starts to evaluate a matter logically. Today in order to develop Critical Thinking and the importance of placing it in scientific fields, several researches have been carried out. Recently, Babamohadi and Khalili (2004) found that there is a significant difference between freshman and senior students regarding their level of CT. But Nafeie et.al (2008) found out different results, that there is no significant difference among first and fourth year nursing students' level of Critical Thinking. This study has been done along with those researches. The main goal of this research is to find out whether there is any relationship between nativeness, age and gender with a level of Critical Thinking of the English speaking students, who are M. A. students studying Islamic subjects in the Islamic College of London. In order to get to this goal, 30 students, 17 male and 13 female from the range of age 23-54 have been chosen as the subjects of the study of whom 14 were English native speakers and 16 native-likes (whose first language was not English). The instrument used in this research was California Critical Thinking Skills Test form B. The test contains 34 questions in 5 different Critical Thinking areas (analysis, evaluation, Inference, deductive, and inductive reasoning) which can evaluate the level of Critical Thinking skills of the students. The results show that there is significant relationship between nativeness and the level of Critical Thinking, but there is no relationship between age, gender and the level of Critical Thinking.