She befriended a pooch. She played tick-tack-toe. She cut a ribbon. She mixed with Washington society. She changed her clothes twice. She sweltered, she smiled, she ran a few minutes behind schedule. In short, the tireless Raisa Gorbachev yesterday took a textbook tour for a politician's wife.

Yesterday began with a crowd of several hundred invited guests out on the South Lawn craning for a glimpse of the Soviet First Lady, who was last seen at the White House in 1987 as she huddled beneath an umbrella during a cold and rainy departure ceremony after the Reagan-Gorbachev summit.

"You brought us a beautiful day," Bush told Soviet President Mikhail Gorbachev at the formal welcoming ceremony. "You also brought back Mrs. Gorbachev. That brings joy to all of our hearts. A hearty welcome to her as well."

Like the weather itself, the welcome was warm and sunny. At one point, Barbara Bush leaned over to touch Mrs. Gorbachev's arm and, with a laugh, tell her something. Mrs. Gorbachev "has been working to improve her English and knows a few expressions and polite phrases," according to a biography released by the White House. Just in case, however, each woman had an interpreter nearby.

A reception followed for VIP guests, among them Mayor Marion Barry and his wife, Effi, who were introduced to the Gorbachevs. After the guests went home, Mrs. Bush led Mrs. Gorbachev upstairs to the family quarters for a late morning tea while their husbands conferred in the Oval Office.

"We had a great visit reviewing our old friendship," Mrs. Bush said later through her spokeswoman Anna Perez, and we're "looking forward to the rest of the week."

With them were Marilyn Quayle; Bush daughters-in-law Sharon and Margaret, who are married to Neil and Marvin Bush, respectively; and the wives of the secretary of state, the U.S. ambassador to the Soviet Union, the assistant secretary of state for European and Canadian affairs and the Soviet ambassador to the United States.

And, of course, Millie, the English springer spaniel whom no right -- or left -- thinking White House visitor would dare to snub.

During their 35 minutes together, Mrs. Bush showed Mrs. Gorbachev around the residence, stopping in the Queen's and Lincoln bedrooms, the Lincoln Sitting Room and President Bush's study, with Millie trailing along. The First Dog also sat on Mrs. Gorbachev's foot and "quivered with pleasure whenever Mrs. Gorbachev spoke to her," Perez said Mrs. Bush told her.

"She said Mrs. Gorbachev and Millie bonded," she added.

Later on, after she changed from her red jacket and black skirt into a gray wool gabardine suit with burgundy blouse, and attended a luncheon at the Soviet Embassy for "American intellectuals," she went to a hot-ticket reception at the Library of Congress.

Hot, as in 90 degrees, fan-your-invitation-in-a-vain-attempt-to-cool-off hot.

More than 400 people, representing official, corporate and social Washington, crammed into the newly renovated southwest hall for the reception hosted by Librarian of Congress James Billington and industrialist Armand Hammer. The festivities included a ribbon-cutting by Mrs. Gorbachev opening a summit-inspired exhibition. What drew them all together in the topsy-turvy world that is the post-Cold War Soviet Union was not glasnost or even caviar, but the first-time-outside-Russia appearance of a group of books and illuminated manuscripts that belonged to the Old Believers, a Russian Orthodox group that split from the official church in 1666.

The exhibition, which was supplemented by rare items from the library's collection, was underwritten by a grant of $75,000 by art collector/industrialist Hammer, who before Mrs. Gorbachev's arrival admitted he felt a particular kinship with the Old Believers. "These were the most prosperous merchants in Russia, from the wealthiest families," said Hammer, who in his lapel was wearing a Soviet secret service pin that allowed him past doors that otherwise would be closed to Americans. "Shchukin, Morozov -- these people were important art collectors. ... Thanks to Mrs. Gorbachev, they have been restored to prominence."

Mrs. Gorbachev's visit to the library, where she was accompanied by Billington, Mrs. Quayle, and a group of Soviet public figures and intellectuals, started with a visit to a room known as the Old Librarian's Office, where she got a look at some of the institution's more prestigious treasures: copies of the Declaration of Independence, the Bill of Rights and the Star-Spangled Banner in Francis Scott's Key's handwriting.

Mrs. Gorbachev was greeted there by Sen. Claiborne Pell, Hammer and Corinne Quayle, the vice president's mother.

"We welcome you warmly," said Pell. "Warmly -- in every sense of the word."

After some guests drifted away, done in by close quarters, a group of Russian Orthodox priests lingered behind. "It's very interesting," Archbishop Clement of New York said of the exhibit. "It's an impressive show of the American people's interest in Russian culture."

After leaving the library almost a half-hour behind schedule, Mrs. Gorbachev went to the Capital Children's Museum in Northeast Washington.

There Syreeta Graham, 9, played metric tick-tack-toe with her. For a prize, Mrs. Gorbachev promised to send Syreeta a picture and autograph. "She just walked up to me and wanted to play," said Syreeta, a poised youngster with a braid down her back.

Mrs. Gorbachev, despite the elbow-to-elbow crush inside the narrow halls of the museum, took the opportunity to hug a few American children who were enjoying the museum, as if she were glad to actually touch some non-official people. Still, she could have copied the museum when she finished, so earnestly did she look at each exhibit with Ann Lewin, the museum's director, and David Fowler, the president of the Learning Center, the museum's umbrella organization. She read the exhibits for each floor out loud in English. She especially asked to see the Communications Center, where the computers and television facilities are located -- but her entourage snatched her away to get ready for the White House state dinner last night.

The Soviet First Lady looked at every picture drawn by Moscow artist Anton Kumankov, and told him and his brother, Nikita E. Pokrovsky, "that she especially liked the title of the exhibit, "No Children in the World Are Strangers." "She said she believed the thought to be true," said Pokrovsky, a fellow at the National Humanities Center in Chapel Hill, N.C. The brothers' mother, Marianna Kutchulova, came from Moscow for the occasion, and spoke to Mrs. Gorbachev.

She heard the Shaw Junior High School band play "America the Beautiful," and she watched 60 J.O. Wilson Elementary School students and 30 from the Model Early Learning Center of the Museum tour the exhibits.

Before she left, Esther Coopersmith, who arranged the visit with the Soviet Embassy, introduced John Matlock, 8, the grandson of the American ambassador to the Soviet Union, who presented a painting by an Armenian child, sent in thanks for American earthquake aid, and a poster. In turn, Gorbachev gave the museum a porcelain dish with a cover shaped like a whale. "She promised to send us the folk tale that it illustrates," said Lewin. "And she promised to come back.