In a country where homeownership has long been the way to build wealth, discrimination in housing is uniquely harmful. It is the chief reason behind the deep segregation in New York’s public schools, which is among the worst in the country. It also helps explain the startling racial gap in wealth in the United States. The median wealth of white Americans is $134,000, according to the Economic Policy Institute. The median wealth of black Americans is $11,030.

Americans would find it unfathomable if schools or water fountains were labeled “White Only,” as was commonplace across the South just several decades ago. They would be kidding themselves to think this kind of discrimination in housing, without the labels, is any less pernicious.

But there’s plenty that can be done about it.

The New York State attorney general, Letitia James, said on Tuesday that her office’s Civil Rights bureau would investigate housing discrimination on Long Island. Officials said anyone with information about possible violations of the Fair Housing Act can call (212) 416-8250, or email civil.rights@ag.ny.gov.

Gov. Andrew Cuomo, a former head of the federal housing department, said in February 2016 that New York would launch a “fair housing enforcement program,” using paired testing and beginning in Buffalo, Syracuse and New York City’s northern suburbs. But Newsday found that the state has not conducted any additional paired testing after that initial round of 88 tests. The Newsday investigation makes clear that the state needs to get up off the couch.

The paired testing Newsday relied upon is expensive, but necessary. The Department of Housing and Urban Development conducts a national test every decade, which reliably finds evidence of discrimination. The most recent results were published in 2012.

Taxpayers need not foot the bill. By licensing real estate agents, New York is conferring a valuable privilege. That license also comes with obligations and, evidently, a need for more supervision. The conclusion is straightforward: New York should impose a fee on real estate agents to fund a vigorous program of paired testing, and agents who are found to be discriminating against clients should face severe penalties.

Yet the persistence of discrimination suggests the need for still stronger correctives.

In Australia and the United Kingdom, home buyers rarely hire their own real estate agents. Instead, the agent selling a home handles the whole process. This is significantly cheaper for buyers and sellers, and it limits the opportunity for discrimination, since buyers decide which houses to visit on their own.