This study examines the possibility that the relationships of intelligence and academic achievement with both extraversion and neuroticism may vary with chronological age. A sample of 741 students in the 15–19 age group worked through a battery of four tests, two of which were tests of intelligence and two tests of achievement in chemistry. The nature of the relationships between performance on these tests and measures of extraversion, neuroticism and chronological age were then expressed as multiple regression equations. The results showed a consistently different pattern of significant relationships for both extraversion and neuroticism with the achievement tests on the one hand and with the intelligence tests on the other. Only the performance on the two achievement tests depended upon an interaction between extraversion and chronological age. There were no such interactions involving neuroticism and chronological age.