Mayor Bloomberg has put reforming New York's famously dysfunctional schools at the top of his agenda, and he's made great strides toward meeting the state-mandated goal of putting a fully certified teacher in every classroom. But even as the city coaxes more qualified teachers through the front door, thousands are leaving out the back.

Somewhere between 40 and 50 percent of beginning New York City teachers leave within their first five years, with the highest turnover rates at the lowest-performing schools. "The cause of the [current] teacher shortage isn't supply but retention, " argues Nicholas Michelli, dean of the City University of New York's teacher training program. "We produce highly qualified candidates, but if we don't fix retention, we'll be doing this every year."

The time to deal with the problem is now, particularly because demographic trends suggest that finding enough qualified teaching candidates is about to get even harder.

We are at the brink of a demographic chasm that experts claim could leave the United States short some 14 million skilled workers by 2020. As the Baby Boomers--the largest, best-educated cohort of workers the world has ever seen--move into retirement, the generation set to replace them is both too small and insufficiently educated to fill the millions of skilled jobs a growing economy is expected to create. Indeed, while the percentage of American workers with college degrees doubled between 1980 and 2000, it is projected merely to inch upward between now and 2020, from 30.2 to 33.6 percent. Yet of the 10 jobs projected to grow the most in the United States between 2000 and 2010, eight require post-secondary training, and six of those require a bachelor's degree, according to the U.S. Department of Labor's 2002-03 Occupational Outlook Handbook. In other words, the gap between the supply of highly trained workers and employer demand for them will widen substantially.

The same trends that will increase competition for these workers in general will shrink the pool of available teachers in two ways: First, as in other industries, the many Baby Boomers who are currently in the classroom will reach retirement age. Second, some college grads who might otherwise consider a career in teaching will be drawn to openings in higher-paid, less trying careers.

To put the problem in context, even with tens of thousands of New Yorkers out of work since 2001, the city has had persistent trouble placing a teacher at the front of every city classroom. Older teachers are already heading for the exits: 5,637 filed for retirement in 2003, the greatest number since 1995, when the city offered incentives for teachers to retire.

"If you're talking about 10 years [from now], at least half the current teachers will have left over that time," says Henry Levin, a professor of education finance at Columbia University's Teachers College. "Teachers don't retire at 65; many put in the minimum amount of time to get a pension [and then retire], because they get worn down."

Even if most teachers did stay on the job until 65, the problem would be far from solved. Right now the average age of the city's public school teachers is 49; nearly 30 percent of the system's 80,000 teachers will reach retirement age within a decade. And that's the best-case scenario.

The city is already working on teacher recruitment and certification, and making commendable progress. But whatever we gain in those areas will mean little unless we can plug the hole at the bottom of the system. New York may not be able to stop teachers in their sixties from taking their pensions and walking off into the sunset, but it has to somehow keep more young teachers from putting down their chalk after just a year or two on the job.

Why does the city have so much trouble keeping young teachers in the system? Money is always a factor, but the last contract the administration concluded with the teachers' union, in 2002, raised pay between 16 and 22 percent over 30 months, a generous increase by any standard. Besides, few go into teaching with expectations of getting rich; compensation is likely secondary to other factors that impel young teachers in the city to leave the profession, particularly difficult work conditions that often include inadequate resources, hostile school environments and dysfunctional administrative systems.

"In New York City schools, working conditions are more challenging, generally speaking," notes Jim Wyckoff, a researcher at the Rockefeller Institute in Albany who has co-authored several studies on New York's teacher-retention issues. "So you're asking that teachers accept lower pay to work [in] more challenging environments."

It's a particular problem for new teachers, who have no control over where they'll be assigned to teach. Frequently the teachers with the least experience--and the smallest paychecks--are sent into the city's most troubled schools, to face challenges that would daunt even veterans. Many of them find it too much, and either leave the profession altogether or seek easier work teaching outside the city.

This is not a big secret; in fact, Schools Chancellor Joel Klein complained last spring to the New York Post that union regulations blocking him from transferring the best teachers to the toughest schools were hurting both student performance at those schools and overall teacher retention. "I think if you put your youngest, least experienced people in the least stable schools, you're going to run into a problem and get demoralized," Klein said.

One program that has had some preliminary success in surmounting these obstacles is the city's largest recruiting and certification initiative, the New York City Teaching Fellows program.

Launched in 2000 under Klein's predecessor, Harold Levy, the Teaching Fellows program aims to increase the number of certified teachers, reverse the overall aging of the teacher workforce and attract new educators with a wider range of experiences. Participants in the program undergo six weeks of intensive training over the summer, which includes master's degree coursework; field work, in which fellows serve as student teachers in classes taught by experienced instructors; and meetings with an advisor for guidance, support and skills development. They are then posted in city schools, where they teach in high-need subject areas such as math and foreign languages. In return, the city pays for their master's degrees in education and starts them at salaries of $39,000 per year.

According to Program Director Jodi Wilkoff, the Teaching Fellows program, which had only 300 participants in its pilot year, now accounts for more than 25 percent of New York's new teachers. The fellows who began teaching in September 2003 included 400 math teachers, 500 special education teachers, and 200 bilingual/ESL instructors--all areas of particular need in the system.

The program is not cheap. The New York Times reported in June 2003 that each Teaching Fellow's master's degree costs the city close to $12,000. This makes it even more important that the fellows reward the city's investment by staying on the job and helping to raise the overall quality of the system. And considering that most fellows are still placed in the sort of high-need assignments that frequently drive young teachers to consider a change of career, these placements constitute a big gamble with public dollars.

Nonetheless, from a retention point of view, there's some evidence to suggest the gamble has been paying off. About 90 percent of the Teaching Fellows who started teaching in September 2002 stayed to begin a second year this September; 74 percent of the previous year's fellows were still teaching as of the end of the 2002-2003 school year. This compares favorably to national figures, as cited by the National Commission on Teaching and America's Future, which indicate that attrition rates for all new teachers are 14 percent after one year, 24 percent after two years, and 33 percent after three. Turnover for teachers working in high-poverty areas--as virtually all Teaching Fellows do--is about one-third higher: 18 percent after a year, 31 percent after two, 43 percent after three.

Wilkoff says trainees' expectations are the key. "The biggest thing has been expectation-setting. Applicants understand what they're coming into," she says. "This program was designed to staff tougher schools."

The program has already evolved to address initial concerns that teachers weren't adequately prepared for the demands of the classroom. "The training is getting better and better," Wilkoff says. "We understand what we can do in seven weeks. There's a teacher cycle of when things get rough and people leave. We're getting better at helping them through that. When they make it through the first year, a higher percentage end up staying."

These are still very short-term results, and it remains to be seen whether this kind of preparation has a positive effect on long-term retention rates. If, however, the program continues to deliver better-than-average retention numbers, perhaps similar techniques could be used to help orient all new teachers, thereby cutting down on the kind of culture shock that seems to send so many running for the exits.

There are certainly many other things that can be done in an effort to retain qualified teachers. To start with, Mayor Bloomberg should push the teacher's union on the concept of implementing a sliding pay scale or system of bonuses that would reward veteran teachers in tougher schools--a concept the UFT has resisted. The mayor's recently launched campaign to make the schools safer for students and teachers alike might help, too. But the Teaching Fellows program suggests that just schooling candidates about what they're getting into might help the city weather the coming demographic storm, and prevent all the mayor's hard-won recruiting gains from going down the drain.