A Harvard history professor's claim that Asian-Americans are the greatest beneficiaries of the University of California's affirmative action ban has come under fire in a recent study.

In a 1999 UCLA Law Review article, Winthrop Professor of History Stephen A. Thernstrom wrote that Asian-Americans gained the most from Proposition 209, a 1996 statewide referendum which effectively ended affirmative action in California public educational institutions.

But a study conducted by William C. Kidder, a researcher with Testing for the Public, a nonprofit organization in Berkeley, Calif., reports that Asian-American enrollment at three University of California (UC) law schools--UC-Berkeley, UCLA and UC-Davis--showed no marked change since 1996.

White enrollment at those schools, according to the study, jumped from just under 60 percent to more than 71 percent of the systemwide UC law school enrollment, while Asian-American admissions increased by less than 1 percent overall, from 17.4 percent to 18.3 percent.

If accurate, the findings contradict Therstrom's study, which seems to show a dramatic increase in Asian-American enrollment since Proposition 209 came into effect.

Thernstrom said he had not yet read Kidder's study, but he said he still stands by his claim that Asian-American enrollment has increased substantially since "the abolition of preference."

"I think it's indisputable from the University of California data in general," Thernstrom said. "The merit system favors high GPAs and SATs and Asians tend to do well in those categories."

Kidder called Thernstrom's study "highly misleading."

Thernstrom's UCLA data, according to Kidder, was particularly problematic.

"He looked at the class just before and just after [Proposition 209]," Kidder said. "The overall number of students in the class increased by 100, but Thernstrom dealt just with numbers, not percentages."

Kidder said his study, which took data from three years before and three years after the institution of Proposition 209, was more comprehensive than Thernstrom's.

"He made the claim the Asians were the biggest beneficiaries," Kidder said. "But the data don't show that."

--Staff writer Alex B. Ginsberg can be reached at ginsberg@fas.harvard.edu.