The number of research doctorates awarded by American universities grew for the sixth straight year and reached another record high in 2007, according to the National Science Foundation's first report from the annual Survey of Earned Doctorates. The overall rate of growth was 5.4 percent.

But while the increases showed strength in many fields, particularly the science and engineering disciplines that have been a source of growing public policy concerns, the number of Ph.D.'s awarded in the humanities dropped by 4.6 percent, to their lowest point since 1994.

And the overall gains continued to be driven by significant numbers of Ph.D.s and other doctorates awarded to non-Americans.

The data on doctorates awarded -- which will be amplified in coming weeks by the release of the Survey of Earned Doctorates, an annual study sponsored by the science foundation and five other federal agencies and conducted by the University of Chicago's National Opinion Research Center -- is closely watched as an indicator of the health and vitality of the American research enterprise and of graduate education in the United States.

As such, much of the data will be heartening -- but with several significant asterisks. At the broadest level, the picture is a positive one: American universities continue to crank out growing numbers of scientists and other researchers to fill college faculties and staff research university, corporate and other laboratories, among other things. And perhaps most importantly, much of the growth is occurring in fields about which there has been significant concern expressed by a slew of recent reports that have inspired increased federal support for research, particularly in the physical sciences.

Over all, the number of research doctorates awarded in 2007 grew to 48,079, up 5.4 percent from 45,598 in 2006. About 80 percent of that gain of 2,500 doctoral recipients came in science and engineering fields, led by increases of 14.4 percent in computer sciences, 13.5 percent in physics, and 7.8 percent in engineering (including 12.9 percent in electrical and 19.7 percent in industrial/manufacturing). Social science fields (which are lumped together -- details will follow in the Survey of Earned Doctorates) grew by 3.3 percent, and psychology by 1.1 percent over 2006.

Only two scientific fields suffered declines from 2006 to 2007 -- chemistry and mechanical engineering, both of which dropped by 1.5 percent, as seen in the table below (chemistry, though, has seen an overall increase of 5.1 percent in the number of doctorates awarded in the field since 1998):

Doctorates Awarded by American Universities, 2006 and 2007

Source: National Science Foundation

The data were decidedly mixed in non-science and engineering fields. The number of doctorates awarded in the burgeoning field of health grew 12 percent, an outcome almost certainly tied to the growth in the number of public health programs and schools emerging in recent years. Doctorates in the field have grown by 42.4 percent since 1998.

The number of doctorates in professional fields (such as business and communication) grew by 8.9 percent, while those awarded in education grew by about 5 percent.

The steepest drop occurred in the humanities, with declines of 6.9 percent in letters (English language and literature, classics, etc.), 2.9 percent in history, and 4.5 percent in "other humanities."

Other highlights of the NSF report include the following:

• The number of science and engineering doctorates awarded to non-U.S. citizens (permanent residents and temporary visa holders) grew at a faster rate (6.0 percent) than did those to U.S. citizens (3.6 percent). In non-science fields, the proportion of doctorates earned by non-U.S. citizens rose by 7.1 percent, while the proportion earned by U.S. citizens grew by just 0.1 percent.
• While men continued to outpace women in the number of science and engineering doctorates they received, the rate of growth in the number of doctorates awarded to women (6.9 percent) was greater than for men (6.2 percent).
• All of the major racial groups except for Asian Americans saw increases in the number of doctorates they received in 2007, with the greatest proportional growth coming among African Americans (9.8 percent) and Hispanic Americans (8.7 percent).