AN EXPLORATION OF THE RELATIONSHIP BETWEEN AN INDIVIDUAL'S PATTERN OF LIVING AND THE RETENTION OF MENTAL ABILITIES WITH AGE WAS MADE AND EVALUATED. THE OBJECTIVES WERE (1) TO ESTIMATE THE EFFECTS OF AN 11-YEAR INCREMENT (50-61) UPON EIGHT MEASURABLE MENTAL ABILITIES, (2) TO ESTIMATE THE EFFECT OF THE GIVEN AGE INCREMENT UPON INDIVIDUAL AND TRAIT DIFFERENCES IN THESE PARTICULAR MENTAL ABILITIES, AND (3) TO REVEAL, VIA THE SCORED LIFE HISTORY, PATTERNS OF LIVING WHICH ARE TYPICAL OF THOSE WHOSE MENTAL ABILITIES AGE HAS TREATED MORE OR LESS KINDLY. NINETY-SIX SUBJECTS WHO HAD BEEN GIVEN THE ARMY ALPHA EXAMINATION IN 1919 AND 1950 WERE RETESTED IN 1961. IN ADDITION, THEY WERE GIVEN A 228-ITEM "LIFE EXPECTANCY INVENTORY." THE AVERAGE AGE OF THE SUBJECTS WAS 19 YEARS IN 1919. THE SUBTESTS OF ALPHA WERE COMBINED INTO THREE COMPONENTS--VERBAL, NUMERICAL, AND REASONING. THE RESULTS WERE CLASSIFIED IN TWO WAYS--(1) THOSE INVOLVING MENTAL ABILITY AND (2) THOSE INVOLVING THE LIFE HISTORY CORRELATES OF CHANGES IN MENTAL ABILITY. FINDINGS INDICATE THAT THERE WERE NO SIGNIFICANT CHANGES IN SUBTEST SCORES OR TOTAL SCORE FROM AGE 50 TO AGE 61. THERE WAS, HOWEVER, A SIGNIFICANT DECLINE ON THE NUMERICAL COMPONENT. IN ADDITION, THERE WERE NO SIGNIFICANT CHANGES IN THE MAGNITUDES OF EITHER INDIVIDUAL DIFFERENCES OR TRAIT DIFFERENCES FROM AGE 50 TO 61. (HB)