Whitman High School senior Alison Dietrich shopped for days before she found the prom outfit with the look she wanted -- long, silky, Princess-style -- and a price tag she liked -- $75 for gown and overjacket.

"One of my friends bought a prom dress for $175, but I just couldn't pay that," said Dietrich, a doctor's daughter who worked part time as a Drug Fair stock clerk to help earn money for the activities and the accounterments that she wanted as part of her last year in high school.

Besides the prom grown, Dietrich said, her costs included a $3 boutonniere for her prom date, $92 senior ring, $12 yearbook, $15 senior dues for cap and gown and other commencement expenses, $15 senior banquet ticket, $40 banquet dress, $70 commencement outfit including dress and shoes, and $40 for her share of the graduation supper party she is having with two other seniors.

Altogether, that works out to $362, and for many graduating seniors these days graduation can cost hundreds of dollars more.

As with everything else, the cost of graduating from high school is rising steadily. Renting a tuxedo for the senior prom costs about $10 more at Woodward & Lothrop this year than last. Some schools have increaed senior dues, which pay for cap and gown and commencement hall expenses. At Whitman, the senior dues are $15, up from $11 two years ago. And some of next year's graduates already have a preview of how much more they have to pay for class rings. The price for one popular 10-carat man's gold class ring purchased by 1981 Fairfax County seniors was $91.80. But the price for 1982 graduates for the same ring is $149.20 -- a 63-percent increase that the ring vender attributes to gold price increases.

To keep her costs down, Dietrich didn't buy graduation announcements."I decided to just write letters instead," she said. In addition, she was careful to select on pair of white strap shoes that would work with both her prom dress and her commencement dress.

Even so, many Washington-area seniors get by for less than Alison Dietrich. Jeff Pellegrino, a senior at Fairfax County's Robinson Secondary School with a part-time job in a law office, estimates that his expenses will total $271 by the time the celebration ends.

In contrast, the tab for some others approaches the $1,000 mark. Melanie Goodloe's graduation from Einstein High School in Montgomery County is costing $844. That includes $300 for the senior trip to Daytona Beach for one week, $100 for clothes for the trip, a commencement buffet for friends and neighbors and traditional items such as senior ring, yearbook and class dues.Goodloe, like many other seniors, worked as a sales clerk to help pay for her expenses.

But no matter what their budget, the consensus of the gradutes and the parents participating in the rites of graduation seems to be that the price is well worth it.

"This is a once-in-a-lifetime affair," said Marcine D. Goodloe, Melanie Goodloe's mother. "My daughter has made good grades and taken great pride in her school and in her work. And when you have a school like Einstein where students and teachers are dedicated, you should encourage graduation activities that they can look back on.

"I think they deserve it."

Psychologists view the graduation experience as an American cultural phenomenon. "It has become, in a sense, our way of honoring the passage of that person into the adult world," said Robert Jardin, who works with adolescents in private practice and through the Montgomery County Department of Health counseling programs.

Over the years, certain rituals have grown up around the event: the graduation ring, the senior prom, the commencement party. "They perpetuate themselves, and families with the money to spend feel obligated to do so," Jardin said.

Graduation does have its dark side, however.

Financial and social pressures can turn this traditionally good time into a nightmare for some students, Jardin said. "There are kids who want to go to the senior prom, but don't have anyone to go with. That can leave them with feelings of rejection."

Others may not attend events because they don't have the money or don't want to spend as much as they think would be necessary to enjoy the evening.

Meg Curlin, a Whitman High School senior, said she chose not to attend her prom.

"It was too expensive -- about $200, Curlin said. She said she was counting $30 for prom tickets, up to $125 for a dress and $50 for dinner. "Besides that, the boy rents a tux. There is gas for the car. And some people go to the beach afterward. It really adds up."

For Jeff Pellegrino, the night added up to about $80.

That included $10 for the girl's corsage, $55 for dinner for two at the Prime Rib in downtown Washington, $7 for Pellegrino's share of a room for a preprom party with several other couples, and $5 for the post prom visit to Sambo's for a sundae. The evening, which began at 5 p.m. and ended at 5:30 a.m., also included an early morning breakfast party at a friend's home and a visit to the Washington Monument, where "I sat and contemplated my seniordom." But at least both of those activities were free.

"I got off pretty cheap," Pellegrino said.

There were two reasons for that, he said. As class president, he didn't have to pay for his tuxedo rental -- it would have cost him $50 otherwise.And tickets for Robinson's prom were free, thanks to student fund-raising efforts that Pellegrino had helped promote.

"This is the first time that any senior who wanted a ticket to Robinson's prom could get one free," said Pellegrino, who had campaigned for class president on a platform promising a free prom.

Money to pay for the prom came from a powderpuff football game, a beauty pageant, a magazine drive and other student events.

School administrators throughout the Washington area say they are aware of the squeeze on family pocketbooks at graduation time. And they generally endorse student plans like the free Robinson prom that will keep senior activity costs down so that a maximum number of students can participate.

At the District of Columbia's Ballou High School, for example, seniors scaled down plans for a trip, Last year participating seniors paid $250 each for a four-day visit to Florida's Disney World, Daytona Beach and Cypress Gardens. This year's seniors took a one-day outing to Kings Dominion with a $10 round-trip bus fare.

Dennis C. Johnson, Ballou's principal, played down the cost of graduation:

"The basic cost here is $17.50 for the commencement hall, the cap and gown and the class gift, and they don't have to pay that if they don't want to go to graduation."

For the student who wants extras, such as the class ring, yearbook and prom night festivities, the average cost can run about $150, Johnson said.

Some school principals are decidedly less enthusiastic about student fund-raising activities, however.

"We deemphasize that at Crossland because having 15 people work all year to reduce prom tickets by $2 isn't that useful, " said Jerry Howie, principal of Crossland High School in southern Prince George's County.

Tickets to Crossland's prom at the International Inn in downtown Washington were $42 per couple. "I have no problem with that [price]," Howie said. "If my wife and I could have an evening for $42 in a D.C. hotel, where you get to dance for a few hours with bank music and you have a meal of steamship round of beef, shrimp newberg and a selection of vegetables -- well, we would jump at it."

At Einstein High in Montgomery County, the effort to hold down graduation expenses attracted the support of students, parents and school faculty. When students discovered how much they would have to pay for a hotel ballroom for the senior prom, they canceled the reservation and arranged to have the prom in the school gym. With the help of the school art teacher, seniors made elaborate decorations: a gazebo, a canopy to cover the ceiling area and panels depicting spring flowers. A group of parents then volunteered to prepare and serve breakfast at the prom.

Tickets would have cost $30 per couple if the prom had been held at the hotel as planned originally, said Principal Allan Halper. But the gym prom cost only $20 per couple.

Ultimately, each senior and his or her family decides how much they are willing to spend on the graduation experience.

"Some smell the roses and others buy the entire rose garden," said Crossland's Howie.

To pay for the cost of graduation, families typically make an extra effort to come up with extra money. Howie believes he knows why: "Parents want the kids to have as good a memory as they can afford . . . . and even during inflation we all love to celebrate and that is the last thing we will give up."

But in addition to family willingness to underwrite costs, many students work to earn money for graduation expenses. John Rumbaugh, a Montgomery County senior, saved $150 from his restaurant job to pay for prom tickets, his date's corsage, a rented tuxedo, dinner for two and gasoline. Sandra Walker, a District of Columbia senior, helped pay for her $78 prom dress with money she earned from teaching dance classes. And Tom Frocke, a Montgomery County senior, paid for his $222 senior trip from his restaurant busboy paycheck.

One way that families generally hold down costs for parties is by going in together and preparing the food themselves. Others economize by making their own prom clothes.

Vanette Rosser, a Ballou senior who has been sewing since sixth grade bought a $6 Vogue pattern and $44 worth of satin and made her outfit in less than one day. The ensemble, which included a jacket, would have cost more than $120 at a downtown department store, Vanette said.

But one corner that many graduates refuse to cut is the fancy restaurant meal on prom night.

"I offered to have a dinner at home," said Rita Rumbaugh, whose son John, an Einstein student, had tried to reduce graduation bills by skipping the senior ring and by wearing a suit he already has to commencement.

"But John wanted to go out to eat on prom night. He wanted to go to the best restaurant in town. Money was no consideration."