The Changing nature of the society and reconstruction of youth aspirations and impact of technology makes teaching complicated today. It demands broad and heterogeneous knowledge of subject matter, curriculum and standards, enthusiasm, a caring attitude and love of learning, knowledge of discipline and classroom management techniques, a desire to make difference in the lives of young people etc. To attain all these qualities, teachers have to sustain professionalism .They must also need tolerance, healthy mind set up and positive attitude. When should they attain all these? They have to internalize these from their pre service training period itself. Do our prospective teachers have the right mind set up to become a great teacher? Even though so many traits are involved in good mental set up two traits rationality and tolerance for ambiguity are considered to be most important. These qualities regulate their behavior, thoughts and emotions and help them to pursue their most complicated job effectively. So the researchers were interested to know the level of rationality and ambiguity tolerance of our prospective teachers and conducted a study to examine these qualities. It is found out that our teacher trainees possess only an average level of rationality and ambiguity tolerance. It is also found that there was variation on these traits when cross compared with their optional subject of study. The result revealed there is a positive relationship between rationality and ambiguity tolerance of our prospective teachers. The study projected the need of mental health training programmes among teacher trainees.