Myers-Briggs Type Indicator (MBTI) was examined for its utility as a predictor of intellective behaviors. For beginning, intermediate and advanced high school students measures of GPA, IQ, science achievement, and science aptitude were obtained. MBTI subscales were dichotomized and criteria were analyzed relative to the resultant eight groups. MBTI subscales provided evidence that typology may well be a moderating factor in intellective performance. The intuition (S-N) scale provided consistent indication of typological differences moderating performance. MBTI appeared to be more appropriate for heterogeneous groups and lost its discriminatory utility with homogeneous groups.