If Commencement runs smoothly, it will be a miracle. But Harvard has had a lot of practice.

To keep the approximately 150 Commencement and reunion functions running effectively, organizers must work nearly 24 hours a day, juggling countless behind-the-scene details.

Yet, year after year, the Commencement ceremonies, receptions, and alumni activities have taken place with remarkable grace and misleading ease.

"It will happen," says Alan J. Powers, Commencement coordinator, about this year's celebration. "We've been doing it for so many years that it's pretty organized."

Veterans of the process say that everything comes together in the last moments. "It's a matter of coordination," says Michael N. Lichten, who has organized Commencement for the past three years. "There's a gigantic schedule of what has to happen first."

Before anything could be set up, the campus's one and one half million square feet had to be groomed. Twenty-five full-time grounds workers have been working on that process since February, says Bernard K. Keohan, superintendent of grounds. As soon as the frost was gone, the workers planted flowers and grass, pruned the trees, and re-paved the walkways.

Once the grass was green, the 55 tents arrived. Then came the 6700 rented chairs and 4400 tables, followed by the 20 students who were hired to set them up.

Keeping the grounds in shape during Commencement will require the services of 24 additional student and casual workers, Keohan says.

But that takes care of the outside ceremonies. Before the 3000 alumni and families arrived, their 2500 Yard, River, and Quad "hotel" rooms had to be prepared. The spring cleaning required the services of more than 350 students. The dorm crew workers used hundreds of mop heads, more than 1000 plastic bags, and over 100 gallons of degreaser, says Alan C. Edwards, supervisor of custodial services in the College area.

And then some 8700 sheets, 4400 pillowcases, and 20,000 rented towels had to arrive. In order to make the alumni feel special, the University broke out its crimson "H" insignia blankets, which it uses only once a year.

Although the Commencement celebrations last only 10 days, a full-time staff works on alumni activities throughout the academic year. The major reunions--for the classes which graduated 25, 35 and 50 years ago--take up most of the coordinators' time.

With 410 returning alums from the Class of 1937, this year's 50th reunion is the biggest ever, says Charlie N. Gregg '88-'89, housing coordinator for the major reunions. Finding rooms for this class can be difficult, organizers say, because they try to house the classmates on lower floors, and near the reunion headquarters at Winthrop House.

The Class of 1962 and their families stay in the Yard, where the younger children can be kept safe from harm, Gregg says. Alumni from the Class of '35 live at Dunster and Leverett Houses.

The job of assigning rooms to the alums is occasionally more difficult because some guests place special requests for "a river view in Eliot House," Gregg says. "We do a good job anyway," he says.

But only major reunion-goers are guaranteed on-campus housing. Everyone else is left to fend for himself.

Around Commencement time, most Cambridge hotel rooms are filled with Harvard guests, who made their reservations last year if not earlier. The Harvard Motor Lodge has been booked for three and one half years--since spring of the Class of '87's freshman year.

Most celebrants also made their restaurant reservations early, as traditional and formal restaurants such as Lockober's in Boston and Rarities at the Charles Hotel reported last week that their reservation books were nearly full with Harvard guests for Commencement night.

In the days before Commencement, however, Harvard takes care of the food and entertainment. Alumni, students, and guests will eat 79,000 meals during the 10-day celebration period.

Harvard University Food Service workers started preparing food last week, says Dale M. Hennessey, assistant director for administration, who helps coordinate menus. The guests will consume 14,000 lbs. of salmon, 480 lbs. of asparagus and 1100 pints of strawberries, says Philip R. Bauer '36, senior food buyer for the Food Services.

And that's not all. About 800 gallons of orange juice, 500 lbs. of shrimp, 4000 lbs. of beef, 4200 lbs. of fresh fruit and 384 gallons of special insignia ice cream are also on the menus.

Meals range from morning coffee and danish breaks to sit-down dinners and the traditional Eliot House lunch of salmon and strawberries. Thirteen thousand meals are served on Commencement day itself, including the lunch of fan-cut, chicken marinated with a tarragon vinaigrette, fruit and tea sandwiches, Hennessey said.

In addition, more than 100 special menus were prepared for 50th reunion-goers as well as for the first grade children of the alumni returning for the 25th reunion. Older guests "can't have anything that they really need to chew," and younger ones are served simpler meals like chicken fingers, Hennessey said.

Each age group also has a week's menu of specially-designed activities. Alumni children are divided into five "color" groups, according to age. While returning classmates attend cocktail parties, symposia, and concerts, the youngest "grape" group children will visit the Big Apple Circus, and the college-aged "blue" group will dance at The Metro club.

While the college-age children of the alumni play sports at the Essex Country Club and attend the Boston Pops, 70 Harvard College students will be baby-sitting.

The University hires hundreds of Harvard student workers to stay through Commencement. They work as baby-sitters, bell-hops and drivers, and answer questions at the information desk.

"When the events start rolling, students make sure [they] actually happen," says Gregg. Last year, he says he worked 20 hours a day for four to five days taking care of last-minute emergencies. Because it rained on Commencement day, and the scheduled shuttle buses were filled up or stuck in traffic, the students had to scramble to find enough vans to take 300 couples from the Class of 1936 back to their cars in the Business School parking lot.

Workers at the information booth are routinely asked to solve crisises, including making hotel reservations for alumni. But some student jobs, such as bell-hopping, are often less nerve-wracking and more lucrative, especially when alumni "drop heavy bills," says Gregg.

All in all it is not too difficult to keep the alumni happy. Edwards says he never gets any impatient requests for maintenance services. "I'm always amazed at the good nature of the alumni. I might expect that after 40 years they would come back as grouches, but they're in good humor."