Washington's Mall wore a warm, majestic and innocent smile yesterday as it filled with hundreds of ecstatic school children in scout uniforms and pleated plaid skirts who came to welcome Pope John Paul II to the nation's capital in a hometown sort of way.

Small yellow-and-white papal flags glistened in the soft autumn sunlight. Excited schoolchildren stood on tip-toes to peer curiously at the man in white, wave at him and hope that he waved back.

Signs drawn on cardboard and pictures clipped from newspapers were held high by the crowd, estimated at 7,000 persons. And the only baby to be kissed by the pope during the ceremoney near the Reflecting Pool cried when it was over.

It was just before 11:30 yesterday morning when Marine One, the presidential helicopter, appeared in the sky behind the Lincoln Memorial, glided low over the pool as if it were a tree-lined runway and delivered the pontiff to the front door of the nation's capital.

The pope began waving to the crowd from his window even before the helicopter touched down. He stepped out onto the grass, and -- ignoring the receiving line -- turned to all sides, stretching out his arms and gesturing blessings and greetings.

Raymond Kottler, a 12-year-old Boy Scout from St. John's Chruch in McLean, waved at the pope, and the pope waved back. "It's just great," Kottler said, He cares about little kids.

John Paul's arrival from Chicago marked the first time a pope has visited this city, which is more accustomed to welcoming presidents, prime ministers and protesters, and is more prone to politics than piety.

John Paul II had been here once before; to speak at Catholic puniversity in 1976, when he was Cardinal Karol Joseph Wojtyla of Poland.

But yesterday, the nation's capital put on its best dress -- and a beautiful day -- to greet him in his new role.

Mayor Marion Barry and his wife, Effi, officially welcomed John Paul II to the city, after the pontiff had been greeted by leaders of the Washington archdiocese, including Bishops Thomas W. Lyons and Eugene A. Marino. Barry presented the pope with a gold key to the city.

The mayor praised the pope as "a friend whose warmth and affection has deeply touched our thoughts, and whose eloquence and example have reminded a world too often absorbed with selfish gain that true greatness can only be achieved when the totality of life is committed to giving water to the thirsty, food to the hungry, joy to the hopeless, love to the stranger and comfort to the sick and oppressed."

The pope presented Barry with a papal medal and expressed his happiness to be in the city and his wish that the good weather would continue. He also offered his blessings to the mayor. Then the pontiff was greeted by Fred and Helena Valentine of Blagden Avenue NW, who were chosen to represent all of the families of the Washington archdiocese.

The ceremony lasted less than 15 minutes. There was no microphone, and the pope did not wade into the crowd to greet any of those present. But there were several touching moments as he moved along a receiving line of City Council members and members of the mayor's cabinet.

Council member David A. Clarke (D. Ward 1) was holding Jasmine Gregory Mize, the child of one of his aides. When John Paul II came to Clarke in the receiving line, the pope held the child and gently kissed her on the forehead. After the pontiff left, Jasmine cried.