THE SURGEON general, Dr. David Satcher, has issued an arresting report about the incidence of mental illness, the heavy toll it takes and the fact that it is too little treated. The estimate is that about one in five Americans "experiences a mental disorder" in the course of any year, and that in prosperous nations such as this, mental illness is the second leading cause of disability and premature mortality, after only cardiovascular disease.

Yet nearly half of Americans who have even severe mental disorders fail to seek treatment. That's true, the report says, despite the fact that mental illness is increasingly well understood, and that "a range of treatments of well-documented efficacy exists for most mental disorders." The principal reason for the reluctance to seek care is the continuing stigma that attaches to mental disorders, the report concludes. The stigma "erodes confidence that mental disorders are valid, treatable health conditions." The lack of confidence is reflected in insurance policies that often impose tighter limits on payment for mental than for physical illness. Money thus becomes an issue; the report calls it "among the foremost reasons why people do not seek needed . . . care."

The report endorses what is known as parity legislation as a way of dealing with this: Insurance policies that offer mental health coverage can be no less generous toward that than with regard to physical illness. Then comes the slightly harder part. Though the need is described as considerable, and cost is said to be a major deterrent, the added cost of meeting the need through parity is said to be barely perceptible--a percentage point or two in premiums. (As ever in such matters, the other side of the argument--the business and other groups opposed to parity legislation--make the opposite case that the cost will be vast while the need is trifling.).

A couple of explanations are offered. One is that managed care seems able to have a sizable effect on mental health care costs. But while people may argue with the magnitudes in the report--that fully a fifth of the population suffers a spell of mental illness in any one year, for example--the broader point survives. The country's ability to identify and treat mental disorders has grown beyond its ability to deliver such treatment. Add mental health care, in other words, to the list of structural inadequacies in the health care system--a seventh of the population uninsured, no prescription drug benefit for the elderly, etc. In every case, cost is the central problem in meeting the need. That's not the same as a reason why the need, somehow defined, ought not be met. But the cost does need to be faced, and not obscured.