Critics of standardized tests have long raised concerns that the tests helped fuel inequality because some wealthier students raised their scores through high-priced tutoring. But recent studies have found that test scores help predict college grades, chances of graduation and post-college success, and that test scores are more reliable than high school grades, partly because of grade inflation in recent years.

But Robert Schaeffer, director of public education at FairTest, an organization that opposes standardized testing, said Thursday that the Opportunity Insights analysis had been criticized by other researchers. “Those scholars say that when you eliminate the role of wealth, test scores are not better than high school G.P.A.,” he said, adding that it is not clear whether that pattern is true among the admissions pool at super selective colleges such as Harvard.

Mr. Schaeffer said that at least 1,850 schools remain test optional, including Michigan, Vanderbilt, Wisconsin and Syracuse, which have recently extended their policies. “The vast majority of colleges will not require test scores.” An exception, he said, could be the University of North Carolina system, which is considering a plan to require tests, but only for those students with a G.P.A. below 2.8.

Acknowledging the concerns of critics, Harvard said that it would reassess the new policy regularly. The school said that test scores would be considered along with other information about an applicant’s experience, skills, talents, contributions to communities and references. They will also be looked at in the context of how other students are doing at the same high school.

“Admissions officers understand that not all students attend well-resourced schools, and those who come from modest economic backgrounds or first-generation college families may have had fewer opportunities to prepare for standardized tests,” William R. Fitzsimmons, Harvard’s dean of admissions and financial aid, said in a statement.