EARLIER this month, Mayor Michael R. Bloomberg announced that he and five other wealthy individuals had raised $1.5 million to reinstate the January Regents exams, which New York State had canceled because of budget cuts.

Although praiseworthy as a matter of personal philanthropy, the donation by the mayor and the others, whose names were not disclosed, is highly distressing as a matter of public policy. It is disgraceful that essential components of our public education system now depend on the charitable impulses of wealthy citizens.

At least 23 states have made huge cuts to public education spending this year, and school districts are scrambling to find ways to cope. School foundations, parent-teacher organizations and local education funds supported by business groups and residents contribute at least $4 billion per year to help public schools throughout the country.

In New York City, families and philanthropies are asked to pay for classroom supplies and music and art lessons. In Lakeland, Fla., a church provided $5,000 worth of supplies for an elementary school’s resource room, and paid for math and English tutors. The board of the Los Angeles Unified School District voted in December to accept corporate sponsorships and to allow the placement of corporate logos on cafeteria walls and in ball fields.