N the movies, school principals are generally portrayed in two distinct categories.

There is the baseball-bat-toting disciplinarian, evoked by Morgan Freeman (playing the real-life New Jersey high school principal Joe Clark) in the 1989 movie "Lean on Me." And there is the buffoon forever running a step behind his students, epitomized by the fictional Ed Rooney (played by the character actor Jeffrey Jones) as he pursues the chronic truant Ferris Bueller.

But the job has always been far less colorful than Hollywood would lead us to believe. And it has never been harder on the people in it, a circumstance that helps explain a national shortage that has left some states struggling to find a permanent principal for one of every five schools.

In December, the New York City schools chancellor, Joel I. Klein, followed the lead of educators in Boston, Providence and elsewhere by announcing a corporate-style principal training and incentive program. Those New York City principals who agree to work in failing schools for three years could earn $75,000 in bonus pay, while a farm team of rookie principals is to be developed partly by having them shadow veterans in a leadership academy.

Anyone considering such work would do well to consult a recent graduate of a similar program, someone like Teri Schrader, who is in her second year as principal of the Francis W. Parker Charter Essential School in Devens, Mass., northwest of Boston. Depending on the time of day, Ms. Schrader can be rallying her 350 middle- and high-school students before do-or-die standardized tests, combing Massachusetts' liability codes to assess Parker's potential exposure in a given case, or buttonholing politicians in an effort to extend the life of her experimental seven-year-old public school, which has an annual budget of nearly $2 million.

"I'm constantly likening it to being a theater director," said Ms. Schrader, 42, who as a drama teacher previously directed perhaps 60 productions at schools in Hartford and suburban Massachusetts. "You're utterly accountable, but you're not the one on stage. It's really like directing theater surrounded by a ring of fire."

In the summer of 2000, after nearly two decades teaching drama and art, most recently at Parker, Ms. Schrader decided to enroll in what her family refers to as "principal college." She chose the Greater Boston Principal Residency Network, a part-time one-year training program based partly at Northeastern University. The program follows a medical school "residency" model by placing 10 aspiring principals each year in a mentoring relationship with a veteran principal.

Working under those veterans, the rookies gain hands-on experience and are eventually expected to graduate to their own principalships.

During her apprenticeship, Ms. Schrader, shadowing the principal at Parker, Greg Sinner, embarked on a daunting project: deciding how much the school's teachers and other employees, 62 staff members in all, would be paid. As a charter school exempt from union rules, Parker had no compensation policy during its first five years, and that meant that some junior members of the staff were paid more than veterans.

The arguments were bitter, as some veterans argued for a traditional "step system" in which salaries would rise in automatic increments. Others wanted raises tied exclusively to teachers' performance.

Ms. Schrader was inclined to agree with the latter, until her mentor, Mr. Sinner, who had spent 30 years as a principal in Illinois, talked her down. He explained that far more seasoned administrators than she had failed in other districts to define how a teacher's performance would be judged — no one at Parker, for example, wanted to link teacher pay to students' test scores — and that a fair system linking wages to the subtle work of instruction would most likely be elusive.

"He was the oldest person in the room," Ms. Schrader said of Mr. Sinner, then in his 60's. "He was really good at asking big questions."

In the end, a committee led by Ms. Schrader and counseled by Mr. Sinner forged a compromise: it created three experience-based categories of teacher salaries, and, within each level, a range of increases to be awarded by the principal, partly on the basis of observation in the classroom.

"The conversations where I have been able to inform these teachers of their adjustments," Ms. Schrader wrote in a paper to her colleagues in the principal training program, "have been among the most joyous and unforgettable of my career."

At the end of that school year, when Mr. Sinner retired, the job of principal was Ms. Schrader's. In the 18 months since, she has had few school days that have lasted less than 12 hours.

"I think outsiders function on a movie model of what a school principal is," she said. "I don't think people have a clue how much you love your kids and how hard the work is."