School districts that don't provide a robust pre-kindergarten program are costing their students and even their taxpayers dearly. Yet not all do.

An article Dec. 6 in New York Teacher, the publication of the New York State United Teachers union, cites research studies that say low-income students who had access to pre-K:

Were less likely to wind up in expensive special-education programs later.

Eventually earned more money.

Were more likely to own their own homes as adults.

Were less likely to receive public assistance.

Were less likely to be arrested and jailed.

To advocates of less school spending, those compelling findings still may not win the day. But this one might: A preschool program near Detroit cost $17,599 per child but led to savings and increased tax revenue totaling $184,086 per child. So the benefits are not only educational and social, but financial.

In years past, preschool programs provided by a school district were regarded as luxuries exclusive to wealthy districts. That is no longer true.

Imagine children of low-income parents, very likely with less education than would be expected among wealthier neighbors, being sent to kindergarten to fend for themselves in competition with students getting coached at home. The competition is unfair and unavailing for the poorer students, a situation an effective pre-K could help address.

Pre-K can even out some of the disparities of birth and upbringing.

The programs don't come without some sacrifice, particularly in rural areas. For example, many families -- especially those with single parents or both parents working -- have difficulty lining up care for half days. Transportation can be another headache. If students are to be bused, costs are increased.

State funding is available for districts with pre-K programs, though it sometimes isn't enough. And, if the funding is not renewed permanently, the districts would be facing more thorny choices down the road.

Identifying which districts in our region have pre-K and which don't is not easy, as the information isn't available from a single source. Nevertheless, in 2006-07, of 220,000 4-year-olds in New York state, 72,000 attended preschool, and the forecast is that that figure will increase to 117,000 this year.

Pre-K is a proven enhancement to a child's present and future and appears to be well worth the investment. Intelligence is not enough to ensure a child's success. Environment is equally important. If the educational environment at home is not favorable, pre-K is crucial.