More than a third have been on the job for three years or less, and many experienced principals are preparing to retire.

He has said that learning from experienced principals should be a crucial component of any training program.

For two years, a business executive-turned-principal must report to an experienced principal who can provide education leadership skills the alternate-route trainee may not have.

But the blueprint for a program to mentor new school principals by tapping the wisdom of our experienced principals is a poor example.

Without experienced principals, Ms. Moskowitz suggested, a more school-based approach to special education could easily founder.

Under Mr. Klein's plan, the experienced principals would work in the failing schools for three years, earning a $25,000 bonus each year.

The most recent contract, which negotiators had hoped would keep experienced principals on the job, has actually had the opposite effect.

The fight over tenure dragged out those negotiations for four years, during which many experienced principals retired or went to suburban districts.

New York City's ambitious effort to recruit 40 experienced principals from across the country has fallen spectacularly short.

For the second half of the year, he said, the pairs of trainees will go to a different school to shadow a second experienced principal.