The objectives of the study were: 1. To assess the socio-economic background of the school students and categorize them as per the intra-variables. 2. To assess the environmental conditions available in different institutions. 3. To measure objectively the mental abilities of the concerned students through appropriate intelligence tests in relation to different variations.4. To compute the level of academic achievement of the students with regard to theintra- variables.5. To examine the effect of the predicting variables of SES, School Environment and Medium of Instruction on the criterion measure of mental abilities and academic achievement. 6. To study the interaction effect of SES, School Environment and Medium of Instruction on mental abilities and academic achievement. 7. To determine the effect of mental abilities in kind and degree on academic achievement of school children.

The random sampling technique adopted by the investigator for drawing the sample of 325 boys and girls from two types of management in government schools and non-government schools of Oriya and English medium schools is quite appropriate.

Intelligence Test by Mishra (1984) and SES Scale and School Environment Scale by the Investigator

The study is ex-post-facto causal comparative.

The data have been analyzed using appropriate statistical techniques, both descriptive and inferential. Mean, Median, Mode, SD, t-value and F-value, coefficient of correlation and coefficient of multiple determinations have been accurately computed and well interpreted.

The study includes following findings: • The distribution of scores of the respondents on mental ability test reveals that there is negligible difference in the measures of central tendencies due to sex variation whereas wide disparity in mean and median is observed in case of management variation. • Wide disparities in the measures of central tendency on academic achievement were observed in case of high SES and low SES sub-samples, boys and girls and government and non-government schools. • The mental abilities of the respondents have been found homogeneous in case of sex and medium of instruction variation, but heterogeneous in case of schools under different management and different school environmental conditions. • There existed significant difference in academic achievement of the respondents, of the sub-samples due to management, medium of instruction and school environmental conditions. But there did not exist any difference in the academic achievement of boys and girls. • In differential analysis of the data on mental abilities and academic achievement with respect to SES, it was found that both mental abilities and academic achievement of the respondents differed significantly due to SES variation. • The schools having high level of teacher input, material input, and process input along with adequate schooling facilities were found to contribute significantly in the development of mental abilities and academic achievement. • There did not exist any difference in the mean mental ability scores of the respondents due to medium of instruction variation. But academic achievement of the respondents was influenced greatly due to medium of instruction. • The SES of the whole sample was found to have significant relationship with mental ability and academic achievement. The relationship between SES and academic achievement was found significant but the relationship between SES and mental ability was not found significant. • The SES was found to contribute 54% to mental abilities and 29% to academic achievement. Both SES and mental ability were found to contribute 51% to academic achievement.