Perhaps not since the annual running of the bulls in the streets of Pamplona have King Juan Carlos and Queen Sofia seen a crowd so devoted to Spain as the one gathered at a reception they hosted yesterday afternoon.

Into the Atrium of the Kennedy Center oozed 1,500 invited guests, mainly those who in some way call themselves Spanish -- not Hispanic, as Spain's Ambassador Jose' Llado pointed out.

Before guests even got near the receiving line, the champagne or the buffet plates of quiche and stuffed mushrooms, they were thoroughly checked by a metal-detector-wielding security man. "You'd be surprised at what we find," the security man said. "Cans of tear gas, knives . . ."

At a reception for the king and queen of Spain?

"Oh no, not here," he corrected. "Other times."

Inside, a phalanx of officials lined up on one side, with photographers on the other. In fact, walking by the receiving line of dark-suited, stern-faced officials, you might almost have passed over the king himself, so unobtrusive did he look in gray pin-striped suit, the only one of the bunch smiling. Queen Sofia, in a black-and-white and gold plaid dress, stood by his side, smiling and shaking hands.

Nearby stood Marta Istomin, artistic director of the Kennedy Center, a friend of the king and queen. They reminisced about times spent together in Greece.

After the receiving line, the king and queen literally plunged into the mob to make their way slowly to the other side of the Atrium. Guests who got all the way up to him spoke rapidly, faces pained with earnestness. He listened attentively, brow deeply furrowed, nodding.

"He looked haggard, didn't he?" commented Victor Bonilla, a foreign-service officer of Spanish parentage who attended with his sister, Kristina, who lives in Madrid. "I called her 'Your Majesty' in Greek," said Kristina, referring to Queen Sofia, the daughter of a Greek king, "and in the middle of all these people, she immediately turned and picked it up."

Segundo Medina, who has been a clerk at the Spanish Embassy for 30 years, said the king recognized him. "He said, 'I've known you since I was a prince,' " said Medina. "He was 19 years old when I first met him."

Maria Lopez de Arenosa, 20, whose father is assistant naval attache at the Spanish Embassy, and her two friends almost got to meet the queen. "The ambassador knows me, and he came over and said, 'I'll introduce you to the queen.' So he took us over to her, and the ambassador was just about to introduce us, then somebody pulled her away. We were standing there with our hands out," said de Arenosa, with a giggle, as she put her hand out in demonstration. "The ambassador smiled and said, 'Oh, well.' "