Mayor Marion Barry threw a city-wide pep rally yesterday for the army of political irregulars and many others in the District who had bubbled with hope, joy and enthusiasm when Barry took office one year and three days ago.

But this time, there wasn't much cheering. The enthusiasm had waned and the joy had mellowed. Hope -- largely unfulfilled -- was mostly what remained.

"We were hopeful from the beginning that the mayor had a commitment to working people in the District of Columbia. He's voiced that commitment. Maybe in the ensuing three years of his term, he will show that commitment," said labor leader Ron Richardson.

Barry used the occasion to give a report card on the accomplishments of this first year in office.

But, citing lingering problems in housing, unemployment and public education, he, too, offered a message of sobriety. "We come at a time of celebration, but not jubilation," he said.

"I think in the last 12 months there has definitely been progress in what we've done," the mayor said, adding later, "The next year is going to be better than the first."

He summed up his first year in office by quoting an anonymous "old man from the South."

"We may not be what we want to be. We may not be what we ought to be. We may not be what we're gonna be," Barry said. "But we're better than what we were."

More than 700 persons gathered for a $7.50-a-plate prayer breakfast at the Washington Hilton Hotel and at a $35-a-person luncheon that were patterened after the two days of inaugural activities held for Barry last year.

A crowd of about 300 persons attended a disco party at the Washington Hilton last night.

But at the daytime celebrations yesterday, however, the crowds were smaller, the applause was lighter and the speeches were shorter than a year ago. Even most of the ministers who spoke at the prayer breakfast managed to give their speeches within the time alloted.

There were no brass bands. No one from the White House dropped by. Most of the members of the City Council also failed to attend. And by the time Barry gave his keynote address at the business, labor and professional luncheon, many in the audience had gone.

There were about 15 pickets outside the hotel. They braved nippy winter winds in the chilly hours before the snow fell in the hope of keeping Barry's feet to the fire on his pledge to stop the hotel from expanding northward into the area now occupied by the apartment buildings in which they live.

"Mr. Mayor, Congratulations from the tenants who live behind the hotel," one sign read. "Help us keep our homes."

The day of festivities was itself somewhat unusual. Seldom do chief executives hold official celebrations of the first year in office on anywhere near the same scale as their inauguration.

But the Barry Bunch -- energetic come-from-behind victors who brought a new and younger breed into city government -- have been a commemorating crowd. They held official celebrations to mark the first 100 days in office and the first anniversary of their Sept. 12, 1978 victory in the crucial Democratic primary.

And it is not over yet. Next week, Barry plans to issue a 100-plus-page chronicle of the accomplishments of his first year in office. The document should have been ready for yesterday's activities, but, Barry said yesterday, he did not have enough time to give it a final reading.

After the opening prayers, Barry launched the day's activities by saying almost the same thing he had said at the breakfast on Inauguration Day, "My Lord, What a Morning."

"You have to say this is a great morning," Barry said, looking out on a crowd of about 750 people. Many of them were city employes and ministers, but not the old-line churchgoing crowd who were the mainstay of prayer breakfasts during Walter Washington's tenure.

"I think Marion has some wooing and winning to do in the religious community," said the Rev. Robert L. Pruitt of Metropolitan African Methodist Episcopal Church. "They were so entrenched in other camps that it is difficult for them to realize that the machinery of government keeps moving."

Barry, who has been trying to expand his political base, said after the breakfast that he was not dismayed by the small turnout of ministers. "I've never claimed the support of the ministers. So if they don't come, so what?" he said. "If you had 25 here, that's more than I would have had during the election."

In his first year in office, Barry told the breakfast crowd, he had made city employes act more courteously when answering telephones, began to take the boards off city-owned houses, spent $3.6 million on repairs for public housing and improved transportation and food stamp services for senior citizens.

He repeated his inaugural promise to make Washington a great city. "Only when you believe, can we achieve. You cannot achieve what you cannot conceive," he said. "And I believe Washington, D.C., can be the number one city in the world."

In the afternoon, Barry told about 800 persons at the luncheon that he had helped keep businesses from leaving the city, produced 32,000 summer jobs for teen-agers, encouraged downtown development and introduced plans for a one-stop licensing service for businessmen.

"Our priority," Barry said, "is to make Washington a great place to live, a great place to work and a great place to do business."

Some in the crowds were enthusiastic, but reservations about the accomplishments of the first year were apparent. Few persons could point to clear differences in their lives as the result of the first quarter of Barry's term being over.

What's difference between this year and last year? a reporter asked Bishop Smallwood E. Williams of Bible Way Church, a dean among the city's politically influential ministers, who sat at the dais near the mayor during the breakfast.

"What's different?" Williams repeated, smiling and turning to a companion as he buttoned his fur coat. "I have a cold. That's what's different."