Black students have their choice of college in a way that was not nearly as true decades ago, a fact borne out by the numbers: In 2006, one in five African American bachelor's degree recipients earned their diplomas from historically black colleges and universities, compared to well over a third in 1977.

But even as they are educating a smaller proportion of black undergraduates, historically black colleges and universities are graduating a growing share of black Americans who go on to earn Ph.D.'s in science and engineering, a new report from the National Science Foundation reveals. The results suggest that the institutions are doing something different -- and important -- for the undergraduates they enroll.

The report takes a historical look at the undergraduate institutions attended by African Americans who received doctorates in science and engineering fields over the last 30 years. In some ways, the data show the ebb and flow of the centrality of historically black institutions in the education of black Americans. In the late 1970s, when more than 35 percent of black undergraduates attended historically black institutions, more than 40 percent of black doctorate recipients in science and engineering had earned their bachelor's degrees from those institutions.

But as many predominantly white institutions opened their doors to black students and intensified their recruitment of the best of them through the 1980s and 1990s, the proportion of African American science Ph.D. recipients who received their undergraduate degrees from historically black colleges fell into the low 20s, as seen in the table below.

Interestingly, though, the pattern has shifted in recent years. Even as the proportion of all black undergraduates who attend historically black colleges and universities has continued to decline, the proportion of black doctorate recipients (U.S. citizens and permanent residents) who earned degrees at those institutions has climbed steadily this decade, the report shows:

Undergraduate Institutions of Black Ph.D. Recipients in STEM Fields, 1986-2006

Historically black institutions produced more black Ph.D. recipients than any other type of institution in 2006. Next in line were intensive research universities with 240 Ph. D. recipients, other doctorate-granting universities with 117, master's granting colleges with 96, and baccalaureate colleges with 61.

Black colleges as a group were even more likely to have produced Ph.D. recipients when the numbers are examined per capita based on their enrollments. In 2006, alumni of historically black institutions received 10.1 doctorates per 1,000 bachelor's degrees they awarded to black students, compared to 7.9 percent for non-black colleges, as seen in the table below:

Number of Black Ph.D. Recipients Produced Per 1,000 Black Bachelor's Degrees Awarded 9 Years Earlier

Ansley Abraham, director of the State Doctoral Scholars Program at the Southern Regional Education Board, which aims to produce minority faculty members, said the data "make clear the importance of historically black colleges and universities in producing doctoral recipients." Neither the data nor the NSF report offer any insights into " why a disproportionately high number [of graduates of HBCU's] are going on to seek advanced degrees," Abraham said, but he offered a couple of possible explanations.

First, he surmised that historically black colleges, many of which tend to lean less heavily on standardized test scores in admitting students, "may be on to something in the criteria they use to select kids that is not born out of how they did on the SATs and ACTs -- picking up on drive or something else" that the institutions then nurture once the students are on their campuses, Abraham said. He also said that because graduates of historically black colleges are emerging from their institutions "without the baggage that goes with being a minority on a majority campus," they "perhaps have a little bit more energy and drive to go on for more education. That's just a theory," Abraham said.

Michael L. Lomax, president and CEO of UNCF: United Negro College Fund, attributed the strong showing of historically black institutions to their traditional emphasis on encouraging their graduates to pursue post-baccalaureate education and to an increasing emphasis at many institutions on science and technology. "Our institutions have really emphasized the undergraduate degree as the launching pad, and generally the culture says to go to graduate and professional school," Lomax said.

And at certain institutions, such as Xavier University of Louisiana and Spelman College, students are strongly encouraged toward scientific disciplines and involved in undergraduate research that prepares them for the sort of work they will do in graduate school, said Lomax. "There is a kind of intentionality and purposefulness here."

Lomax said the performance of historically black colleges and universities in producing black doctorate recipients is all the more noteworthy because the institutions receive "disproportionately fewer dollars [in federal research support] than comparable institutions do."

"When you look at the NSF dollars that go to HBCU's, they don't reflect the disproportionate production of graduates in the fields the NSF cares most about," Lomax said. "It would nice to see the money reflect the kinds of disproportionately strong production that is coming out of these typically underresourced institutions."

The following table compares two lists of the top 50 institutions whose African American graduates went on to receive doctorates between 1997 and 2006. On the left are the institutions in pure numbers; the right side shows the number of black Ph.D. recipients that institutions produced for every 1,000 black recipients of bachelor's degrees nine years earlier.