Students in the cafeteria of Wilson High School were eating and talking quietly when Melvin Pickett, 18, jumped up to tell his friends a joke.

Speaking loudly and gesturing, Pickett recounted a brief tale. By the time he delivered the punch line, the principal was standing next to him with a hand on his shoulder.

"Please have a seat, young man," said Michael Durso, reminding Pickett of the school's rules of conduct.

To laughter from the group of students, Durso asked: "Are you getting paid [to be a stand-up comic]? I hope you're not doing that for free."

For Durso, the brief encounter was a small part of a busy day, but for Pickett and his friends, it was a reminder that Durso is always in charge, always watching what students are doing and always enforcing the rules.

"He's strict," Pickett said. "He doesn't let anybody go easy for what they do."

Students who fail to straighten up face a reprimand, a telephone call to their parents, suspension or transfer, Pickett said.

Durso has earned a reputation as a no-nonsense educator who at times has had conflicts with administrators over school rules and policies. Less than two weeks ago, he walked out of Wilson because school officials ordered him to allow a student who had been accused of raping a classmate to remain in school.

Durso returned after the charges against the youth were dropped in D.C. Superior Court.

Durso, 43, has spent half his life working for the District's school system. Since 1982 he has been the principal of Wilson, a 1,600-student school regarded as one of the city's best.

Once an all-white neighborhood school attended by the children of upper middle-class parents, Wilson, at Nebraska Avenue and Chesapeake Street NW, draws students from throughout the city. Sixty percent of its students are black, 20 percent are white and 20 percent are of foreign descent.

"We're a better school than we were before, because of our diversity. Diversity is our strength, there's no question about that," Durso said. "It is our job for youngsters to understand the differences they see in each other as opportunities to learn, be they of another race, another country, or whatever."

Once the city's leader in academic achievement, Wilson now ranks third behind Banneker Academic High School and the School Without Walls, Durso said. But he added that standardized test scores remain relatively high at Wilson, more than half its students are enrolled in advance courses, and it has a generous sprinkling of Merit Scholar finalists.

Unlike many principals who emphasize test preparation as the key to building effective schools, Durso maintains that atmosphere is more important.

"It is my philosophy that, once you have established the proper atmosphere at a school, everything else will fall in line," said Durso. "Students will be eager to come to school, they'll know what is expected of them, and teachers will be motivated to teach."

He said that an important part of setting the proper tone is allowing a principal to have control over what happens at school. That, he said, is what prompted his recent walkout.

Durso explained that he could not, "in good conscience," let the student attend classes. Durso was criticized and praised by students, teachers and parents, with some saying the principal had disrupted the school and others saying that his action exemplified the spirit of Wilson's mascot, a tiger.

School Superintendent Floretta McKenzie, who ordered Durso to return to work, said that she would discipline him for insubordination and breaking school rules but refused to reveal details. Durso said he expected to be disciplined, but did not regret his actions. The protest, he said, was intended to demonstrate to school officials that principals need more control in handling disciplinary problems at schools.

Durso's first job with the D.C. school system was in 1965 as a teacher at Gordon Junior High School. He was transferred to Lincoln Junior High School when it opened in 1967 and taught there for four years before becoming an assistant principal at Roper Junior High. He was transferred to Wilson in 1971 and served as an assistant principal there for six years before returning to Lincoln as principal.

Before he arrived at Lincoln, there had been seven principals there in 10 years, Durso recalled. School officials, including school board president R. David Hall, had said that Lincoln was "falling apart and needed some leadership." By the time Durso left, the school had improved dramatically, Hall said. Although academic test scores still were low, a sense of order and consistency had been created.

Hall described Durso as a "strong" principal.

"Strong principals have a strong self-image and clear set of values about what is right and wrong," Hall said. "They make decisions all day long, so they can't afford to equivocate. Most of our best principals are mavericks and run afoul of the rules from time to time. Durso's the first one who's gone across the line and been insubordinate."

In addition to the recent incident, Durso had been reprimanded in December 1984 by school officials after after he detained about 300 tardy Wilson students outside the school, lectured them on punctuality and the next day sent home about 70 latecomers. In another incident, he was reprimanded and suspended for three days for forfeiting a Friday afternoon football game after failing to reach an agreement with the opposing team to reschedule the game for Saturday.

Durso's "interest in the school goes well beyond the 40 hours and the paycheck. He definitely wants to see to it that there is a conducive atmosphere for education," said LeRoy Lowery, copresident of Wilson's Parent-Teacher Association.

Durso said that he has worked as a mail carrier, a truck driver and an insurance adjuster, but "for as far back as I can remember, I've wanted to be involved with young people."

"The great thing about working in a school setting," he said, "is the opportunity to touch minds and shape lives."

A Washington native, Durso was raised in Northwest and attended the Nativity School and St. John's College High School, both parochial schools. His father, now deceased, was a clothing salesman. Durso, married and with four children, now lives in Silver Spring.

"There are very few monetary or material rewards in education," Durso said. "The real reward is when students come back to see you . . . . Many of them have gotten themselves together and are doing very well, often times against very great odds. I would like to think that I have played a part in their development."

Louis Hall, 28, one of Durso's former students, visited him last week. He explained that he wanted to thank Durso for helping him become a respectable, responsible person. Hall works for the District's Department of Employment Services, helping youths obtain summer jobs.

"Me and my buddies used to do everything," Hall confessed. "We gambled, took other guys' lunch money, we did it all. I didn't go to school for an education . . . . I went to have fun."

When Hall first met him, Durso taught social studies at Lincoln.

"He was a teacher, but we used to kid him because even back then he acted like he thought he was a principal," Hall recalled. "When the bell would ring, he would stay out in the hallway, making sure all the kids were in their classes. He acted as if it was his hallway. It was always clear."

Hall said Durso suspended him from Lincoln several times for misconduct. And later, after Hall was recruited by coaches at Wilson to play football for the school, Hall had more run-ins with Durso.

"Durso transferred me [to another high school], but a year later, after a football game against Wilson, he came up to me and started talking," Hall related. "He asked me how I was doing, and I told him I had learned a lot. He said he could see that I had matured, and he invited me to come back to Wilson to graduate.

"To me, that meant a hell of a lot. It showed that he really cared about me as an individual."