The Supreme Court’s decision to effectively end race-conscious admissions in higher education last month was historic in its own right, removing a tool that the nation’s colleges have used for decades to increase racial diversity on their campuses.

But what started with affirmative action has morphed into a far broader reconsideration of fairness and privilege in college admissions and what it means for American higher education.

On Tuesday, the Education Department announced that it had opened a civil rights investigation into Harvard University’s admissions preferences for the relatives of alumni and wealthy donors. And at what the department billed as a “National Summit on Equal Opportunity in Higher Education” in Washington on Wednesday, more than 100 academics, government officials and education administrators focused on how much is now up for grabs well beyond affirmative action.

“We come together today at a turning point in higher education — perhaps in all of education,” the education secretary, Miguel Cardona, said in his keynote address. “We didn’t ask for this moment, but as leaders we must answer.”

Already, especially at elite colleges, there is widespread discussion of the role of legacy admissions, preferences for family members of donors, and of who benefits from athletic scholarships.

Given the court’s ruling on affirmative action, officials at the conference discussed the importance of developing and expanding other tools to achieve diversity. Those include: recruiting through academic enrichment programs for talented low-income students; improving financial aid; initiating so-called direct admissions, which means automatically admitting students who have met certain threshold requirements; bringing disadvantaged students to campus to generate interest; and making it easier for community college students to transfer to four-year colleges.

Even how the Supreme Court’s ruling will be interpreted is in flux.

On July 12, Students for Fair Admissions, the plaintiff in the Supreme Court cases, sent a letter to 150 public and private colleges essentially warning that the organization would be watching them for signs that they were skirting or violating the court’s decision.

But at Wednesday’s summit, two federal officials and interpreters of the court’s decision fired back, saying that they, not a private group, were the enforcers.

“I have heard about groups who are not the Department of Education or the Department of Justice sending schools notifications about what they say the law is and what they want you to do,” Catherine E. Lhamon, assistant secretary in the department’s Office for Civil Rights, declared to the audience.

“I offer you this: You will know when you hear from us,” she said. She did not name Students for Fair Admissions, but everyone in the audience seemed to know what she was alluding to and responded with clapping and laughter.

Ms. Lhamon said that the court did not rule that working to achieve diversity was unlawful, and that her office would be “ready to help you, including through technical assistance,” in determining how to comply with the ruling.

Kristen Clarke, assistant attorney general for civil rights in the Justice Department, said that it was working on a “resource document,” publicly available next month, that analyzes the court decision for colleges. Discussion of race was not flatly forbidden, she said. A Black student might want to write an essay about becoming interested in civil rights law after a field trip to the courthouse, or about learning to cook Jamaican dishes from her mother — both experiences that she had, Ms. Clarke added.

As successful as race-conscious admissions have been in creating a pipeline for Black and Hispanic Americans to leadership positions, some social scientists suggested that it also allowed colleges to shirk a broader responsibility to facilitate social mobility.

Racial preferences “kind of let these schools off the hook for a while,” Mitchell L. Stevens, an education and sociology professor at Stanford University, said.

Still, doing away with racial preferences, without some major innovations to replace them, will have enormous impacts on diversity, experts said.

Economists who examined admissions data from Harvard and the University of North Carolina found that, under a policy where Harvard were to remove preferences based on race without changing other aspects of its admissions process, the proportion of admitted Black students would fall by about two-thirds. The proportion of admitted Hispanic students would fall to 7 percent of the total, from about 13 percent. The estimated decline was similar for the University of North Carolina.

Zachary Bleemer, an economist at Princeton who has studied alternatives to race-conscious admissions, said that he saw little reason to retain legacy preferences, but that doing away with them would affect “a relatively small number of students across the Ivy-plus system” and was unlikely to have a democratizing effect at the national scale.

At selective public universities, “top percent’’ policies that guarantee admissions to high-performing students at all public high schools in a state had helped increase racial diversity, Dr. Bleemer said. He suggested that private universities, especially those in urban areas, could similarly provide large and transparent admissions advantages to top students at local lower-income schools.

The Biden administration’s investigation of Harvard’s legacy preferences comes in response to a complaint by civil rights advocacy groups that the system favors white applicants.

There is no indication that a similar investigation is scheduled for other schools.

Richard Kahlenberg, an education consultant who is a proponent of class-based rather than race-based admissions, said that there had always been a symbiotic relationship between racial preferences and legacy preferences.

“Supporters of racial affirmative action liked that they could point to legacies as evidence that college admissions was not about meritocracy,” he said in an email. “And supporters (and beneficiaries) of legacy preferences liked racial affirmative action because the racial diversity it produced gave the superficial appearance that the system was fair and open to all.”

The court’s decision, he said, meant that “the grand bargain has collapsed,” and that legacy policies are suddenly more vulnerable than before.

But, for the most part, college officials focused on practical issues more than on theoretical ones.

Christina Paxson, the president of Brown University, talked about how important it was to support disadvantaged students once they got to campus. For instance, she said, opportunities like research and internships had to be advertised, because they were often “invisible” to first-generation students.

Uma M. Jayakumar, an associate professor of education at the University of California, Riverside, who did not attend the conference, said that for Ivy League colleges — where as many as 30 percent of students are children of alumni, donors and faculty, or are recruited athletes — changing the system of preferences could be meaningful in changing the demographics of the college. But doing so could be costly, too.

“Harvard has gone to court and fought for diversity,” Prof. Jayakumar said. “I would say, let’s see what they’re really willing to do.”