72 10.5-19.8 yr old students representing the top 0.03% of their age group in intellectual ability, who were identified by the Study of Mathematically Precocious Youth (C. P. Benbow and J. C. Stanley (see PA, Vol 66:10019)), were tested along with their parents using a battery of specifically designed cognitive tests. These children had less intelligent but yet quite bright parents. P. E. Vernon's (1961) model of intelligence best fits the results. Two factors explained most of the variance in the performance of the students and parents: Verbal-Educational and Practical-Spatial-Mechanical. Moreover, there was potential evidence for a general factor. Among the children, who were mostly past puberty, age related to development of verbal abilities but not to spatial or mechanical abilities. Sex differences favoring males were found on the spatial ability and mechanical comprehension tests.