The main focus of the present study was on analytically studying the I.Q and cheerfulness level of male students registered with HEC-recognized institutions and HEC-recognized Deeni Madaris at post-graduate level. A convenient total sample of 700 students (including 350 each of the two sub samples) fulfilling the conditions was tested. The Demographic Information Performa (DIP), Zahanat Paima (Urdu adaptation of ‘Otis Tests of Mental ability and Jaiza Mizaji Kafeyaat (Urdu adaptation of Thorndike Dimensions of Temperament were administered on the participants. The data obtained was analyzed using SSPS. T-test for independent samples was run to find the difference between the students of HEC-recognized institutions and Deeni Madaris on cheerfulness and I.Q level. The findings of the study revealed that students of HEC-recognized institutions were significantly higher on the temperament dimensions of cheerfulness. No significant differences were found between the two groups on I.Q levels. Number of sibling, father education and I.Q level showed significant effect. Moreover, the findings suggested a weak significant positive relationship of I.Q level with cheerfulness. The study has great significance as it evaluates the differential effect of educational environment (sixteen years) of Deeni Madaris and general educational institutions on the development of temperament dimension of cheerfulness in the respective students.