King Juan Carlos I of Spain will deliver this year's Commencement address, University officials announced yesterday.

Juan Carlos, whom many have credited with guiding his country from authoritarianism to democracy, is the only first-choice candidate to accept Harvard's offer in four years.

The monarch's speech will address Spanish-American relations, David A. Aloian '49, executive director of the Harvard Alumni Association which runs the Commencement exercises, said yesterday.

This year's announcement comes on the earliest date ever, Aloian added. In fact, Juan Carlos accepted in December, but the Alumni Association decided to keep the information under wraps until later in the year.

A statement was released yesterday because "We decided that there was no way we could keep this a secret late into the spring," Aloian added.

Last year, the Mexican author Carlos Puentes was named Commencement speaker on May 19, a mere three weeks before the ceremonies, after a much-publicized offer to Polish union leader Lech Walesa fell through (See story below.)

This year, in contrast, the offer was out by October, tentatively accepted by November, and officially accepted in December, Aloian said.

Juan Carlos the Man

The King of Spain is described as both a forceful, charismatic leader and a humble father of three.

The hand-picked successor to Generalissimo Francisco Franco--who ruled Spain with an iron grip from 1939 to his death in 1975--Juan Carlos succeeded to the throne and promptly instituted a constitutional monarchy.

"It was so quick that you didn't know the policies of who you were voting for." Juan Corbello '85, a transfer student from the University of San Louis in Madrid, said yesterday.

The transition earned Juan Carlos an international reputation, Corbello added, as well as a nomination for a Nobel Peace Prize.

"He has become a symbol of democracy and political negotiations," said Terry L. Karl, assistant professor of Government.

"This transition is really one of the great success stories of foreign affairs," added Robert D. Putnam, professor of Government.

But by all accounts, Juan Carlos has not let success go to his head. Since he warded off a military coup in 1981, the urbane, cosmopoli- lan monarch has lived modestly in his palace in Madrid.