Hundreds of Saudis have emerged as millionaires, and a few as billionaires, from the past decade of boom here, but few have had such a clear vision of what to do with their new-found fortunes as Rafiq Hariri.

Hariri, son of a poor shopkeeper from Sidon, Lebanon, came here as a teacher in 1965 and 20 years later is one of the kingdom's wealthiest commoners.

Hariri, 40, says he has not been content, however, with just making money hand over fist as a contractor. He also has played the role of Saudi point man and peacemaker in Lebanon, poured millions of dollars into cleaning up and restoring war-shattered Beirut, built an entire hospital complex near Sidon and now plans to send 6,000 Lebanese students a year abroad for education.

Another self-appointed task, he said recently, is to project a new Arab image in the West. Hariri insists that the bad publicity some corrupt businessmen and playboys have given to the Saudi is unfair.

"I admit we have rich Arabs who did something to give Arabs a bad image in the West," he said in an interview at his spacious mansion on the outskirts of Riyadh. "But can you name 10 of them? We are 150 million Arabs; if you cannot name 10, it means there is something wrong."

The new counterimage he is trying to create is the Arab millionaire as Islamic philanthropist and social activist, concerned about the problems of his society and trying to do something about them.

Last year he was honored in Washington by the Save the Children organization for his relief efforts in Lebanon, including matching $500,000 in donations to the group to help needy Lebanese children.

Possession of wealth imparts a "duty," according to Hariri. "You are part of the society. You cannot just sit around and watch and enjoy your money without participating in that society. Our religion is based on that."

Hariri's own rags-to-riches story began when he was 13, picking oranges and apples in the orchards around Sidon for the equivalent of about $2 a day and dropping out of school to support his bankrupt father.

After graduating from Beirut's Arab University with a degree in business administration, Hariri went to Saudi Arabia to teach but quickly transferred to a firm of accountants. From there, he jumped into construction work, and in 1972, on the eve of the great oil boom, he started his own small company.

At first, he lost money, he said, but in 1976 his big break came. He was working as a subcontractor on the Intercontinental Hotel in Taif, a mountain resort and the Saudi summer capital, when word came from the king that the hotel had to be finished in eight months.

Hariri met the challenge, established his reputation and bought a 40 percent interest in Oger-France, the main contractor for the hotel. He had caught the eye of the royal family.

His next big break came in 1980, when the king, upset by the high bids on a vast new government center called Sunrise City, to be built outside Dharan in the Eastern Province, asked Hariri to price the job.

"The lowest bid was 3.15 billion riyals [$885 million] with the work done in 42 months without decoration or furniture," Hariri said. "My price was 2.3 billion riyals [$657 million], and the work done in 24 months including decoration and furniture."

His French partners "thought I had made a big mistake and wanted to sell out their shares," he said. So Hariri bought them out, became sole owner of Saudi-Oger, and built Sunrise City on time.

Hariri now is clearly the royal family's favorite contractor. During the past two years, he has averaged $2 billion annually in gross income on construction work across the kingdom, building hospitals, palaces, conference centers, schools, and now, in Riyadh, his third government center, for $1.1 billion. In Medina his company is building a $285 million facility for mass printing of the Koran, and will be paid $140 million a year to operate it.

Although he is now a Saudi citizen, Hariri has worked to rehabilitate war-shattered Lebanon. He began in 1979, building a huge hospital complex with a nursing school and university teaching center, at Kfar Falous, in the mountains outside Sidon. He said he has spent $150 million so far, but the Israeli occupation and harassment by the Christian militia have halted work.

After the Israeli siege of west Beirut in 1982, Hariri used his local subsidiary, Oger-Lebanon, to clean up rubble, raze bomb-blasted buildings and clear mountains of garbage from the streets. He also began restoring the old downtown business center along the Green Line separating Beirut's Moslem and Christian halves.

He estimated that he has spent $100 million on such projects there and in Sidon.

A current project is a scholarship loan program for 6,000 Lebanese high school graduates a year, sending two-thirds of them to universities in France and the United States and the rest to Lebanese schools. The first group of 300 is about to go to the United States, including 26 who are to arrive at Georgetown University in January to begin studying English.

"All they have to be is poor and Lebanese and have a high school diploma," Hariri said. "We are recruiting them from all over Lebanon -- Christians and Moslems alike."

The recipients of the long-term, low-interest scholarship loans must agree to return to Lebanon and work there for as long a period as they studied abroad -- a stipulation that Hariri hopes will reduce the current brain drain in Lebanon. He estimates that the program will cost an average of $6,000 a student, or $36 million a year.

"This is the only thing I can do and nobody can stop me from doing it," he said, alluding to the renewed sectarian fighting in Beirut that has stopped his restoration work in the city center and the Israeli occupation of the Sidon area that has made it impossible to continue work on the hospital center.