This article discusses the timeframe of programs of doctoral study. By the time the 10th anniversary of their enrollment in a Ph.D. program has rolled around, about 57 percent of doctoral students have their terminal degrees in hand, according to new data from the Council of Graduate Schools. Perhaps the most interesting of the council's findings is the suggestion that the 10-year mark may be too early to write off some students as "noncompleters." In some fields (mainly engineering and the sciences) most people complete their Ph.D.'s after 6 or 7 years of doctoral study. After that, the percentage of students who have completed their degrees begins to level off. However, in the social sciences and in the humanities, even into the 8th, 9th, and 10th years of study, the percentage of students who have completed their degrees slowly continues to rise. Trends in the data suggest that still more humanists and social scientists complete their degrees after 11 or 12 years in Ph.D. programs, and may call into question the wisdom of setting time limits on doctoral study, as some universities do. In addition to low completion rates for humanities, the study found one of the highest attrition rates. Unlike mathematics and the physical sciences, where almost all of the students who leave do so by the third year of study, in the humanities, only half of the students who will eventually drop out are gone by year three. The remaining departures are staggered out over the next seven years, with almost 3 percent finally throwing in the towel after investing 9-10 years in the doctoral program. Other findings in the study question conventional wisdom about Ph.D. completion: contrasting with earlier studies, the council's data suggested that the difference between completion rates for departments with large and small numbers of students is insignificant, that public institutions rather than private yield better Ph.D.-completion rates, and that advisers are most available at the beginning of programs and least available during the dissertation-writing phase. (Contains 5 graphs.)