Duke is where Tweedy himself went to medical school, and he told me that although most of his classmates there were from colleges more selective than U.M.B.C. and families with more money than his, “I scored in the top 20 percent of my class during that first year of basic science classes, which are the toughest part of med school.” U.M.B.C. had prepared him well, not just academically but also, he said, by making him feel that he was “part of something more than just your individual attainment.”

He recalled that before he decided to go there, several Ivy League colleges tried to recruit him — for basketball. In contrast, he first came on to U.M.B.C.’s radar because of his aptitude for science.

More than one in four U.M.B.C. undergraduates qualifies for federal Pell grants, meant to serve low-income families. About 45 percent are white, while 18 percent are Asian-American and 16 percent are African-American.

From the ceiling of the student commons hang flags of countries from which students have come. There are more than 100. It’s a kind of kaleidoscope, and as I walked under it with Freeman Hrabowski, U.M.B.C.’s dynamic president, he stressed the school’s determination to “connect students to people different from themselves and lives different from their own.” The young men and women who ate, talked or studied at almost every one of the tables around us were a mix of colors, and I couldn’t map the room in terms of any obvious tribes or cliques.

Diversity, socioeconomic or otherwise, doesn’t factor much into U.S. News rankings, though a broadening of perspectives lies at the heart of the best education. U.M.B.C., with its acceptance rate of nearly 60 percent, places 159th among national universities.

One of the main factors in a school’s rank is how highly officials at peer institutions and secondary-school guidance counselors esteem it. But they may not know it well. They’re going by its reputation, established in no small part by previous U.S. News evaluations. A lofty rank perpetuates itself.

Another main factor is the percentage of a school’s students who graduate within six years. But this says as much about a school’s selectiveness — the proven achievement and discipline of the students it admits — as about its stewardship of them.