What counts as a D.E.I. program in a school? And how do such programs differ from simply learning and talking about race and identity?

Those questions have been central to local education debates over the past five years. Now, they are most likely to become even more pressing, after the Trump administration notified all 50 states on Thursday that public schools could lose federal funding if they engage in the use of D.E.I. to “advantage one’s race over another.”

The letter presents the clearest threat yet to the country’s largest source of federal funding for K-12 schools — Title I, which supports low-income students. (Federal dollars account for about 8 percent of total K-12 education funding.)

President Trump has previously pressured schools not to recognize transgender identities. The new directive focuses on the categories of race, color and national origin. The document sent to states cites Title VI of the Civil Rights Act, which seeks to prevent discrimination, and the Supreme Court’s 2023 decision overturning affirmative action in college admissions.

The administration has not offered many examples of K-12 programs it considers illegal. But here are the types of initiatives that could come under scrutiny.

Single-Race Affinity Groups

Schools sometimes separate students by race, either to provide targeted support or in an attempt to foster more open discussions about race itself.