Questionnaires were sent to U.S. high schools soliciting information on former students who had earned doctorates. The questionnaire provided data on grades, rank in graduating class, and mental test scores. The grades were summarized into four grade-point averages (GPA's), one each for English and foreign languages, social studies, mathematics, and science. Data on the PhD's (and their classmates) were compared by sex, by type of school, by size of graduating class, and by region of the country. The PhD's were also compared by year of doctorate and by field of specialization. Some of the conclusions are as follows: despite the massive increase in doctorate production, there has been no measurable change in ability level of the PhD's; the doctorate-holders are, on the average, one and one-half standard deviations above the mean of the general population in measured ability. A random sample of the girls graduating in the same classes as the doctorate-holders scored slightly lower than their male counterparts on standardized tests, but achieved better grades, particularly in verbalistic subjects. (Author/BB)