After a decade of boom and prosperity, Saudi society now faces its first potentially serious strains as the government sharply cuts spending, lucrative contracts dry up and the kingdom is forced to live within new, more normal, limits.

The question is whether this highly subsidized Arabian-style El Dorado, built on its still-enormous oil riches, can learn to cope with the effects of a $70 billion drop in income during the past three years.

Many Saudi officials are actually expressing relief over the advent of what they call the "new era," hailing it as an opportunity to slow down and imbue a spoiled society with normal economic expectations and work habits.

Nonetheless, signs of the strains of adjustment are becoming apparent, particularly at the top levels of Saudi society -- the royal family, the government and the kingdom's newly rich. The strains raise issues that go to the heart of the two-centuries-old ruling House of Saud, including whether it should run the country as a family enterprise or a modern state.

A struggle for control of the purse strings already has pitted top members of the royal family against prominent commoners in the Cabinet and made the job of Mohammed Ali Abal Khail, the finance and economy minister, one of the most powerful and delicate in the kingdom.

In recent years, Saudi society has grown more varied and complex, with the development of a vast business community, a highly trained stratum of technocrats and bureaucrats, a rising middle class of foreign-educated commoners and a more assertive Islamic religious establishment.

Western political analysts are fond of saying that "there are no politics in the kingdom." This may be true in the sense that, in addition to having no political parties, there is no struggle over power or even serious questioning of the Saud family's right to rule.

But interest groups similar to those in the West have emerged out of the past decade of spectacular economic development and social change. They are quietly fighting over the shrinking economic pie as well as the norms and orientation of this ultraconservative society that follows the puritanical traditions of Saudi Arabia's strict Wahhabi sect of Sunni Islam.

The sweep of change that has hit Saudi society is brought home when one reads about King Abdulaziz ibn Saud, the revered founder of modern-day Saudi Arabia, and his struggle to unite the unruly tribes of the Arabian Peninsula into a single state during the first third of this century.

Today, a visitor gets little sense that these tribes still exist, let alone have any importance. The proud Bedouin seems fast becoming a vanishing species, his tent, blanket and tea cup relegated to museums and the entrance of hotels such as the Hyatt-Regency in Jeddah. Camels are even hard to find in many parts of the kingdom.

The last published Saudi census in 1974 said the nomads numbered 1.9 million out of a total population of 7 million (a total inflated by the presence of foreigners who make up most of the work force). The nomads now are estimated to number no more than 300,000 and may be as few as 70,000, according to some Saudi and western scholars.

The 25,000-man National Guard serves as a kind of resting place and "gigantic welfare society," as one western adviser put it, for those tribesmen not yet integrated into the new city-based Saudi society.

The wealth and glitter of urban life have scattered the tribes. Now, the family is becoming the main social unit, a change reflected in the tendency to drop the part of the Saudi name indicating tribal affiliation and adopting western-style surnames.

While tribalism still has a role in social identification and lobbying, Abdullah Masri, assistant deputy minister of education and an American-educated social anthropologist, said, "it is not a factor in the rise of the individual here."

Saudi Arabia in the boom decade of the 1970s was really a repeat of "the American dream," in the sense of "unbounded opportunities for all -- no holds barred," Masri said.

Another high-ranking official, asked whether tribalism still was considered in making government appointments, thought for a moment and then replied: "Yes, the doorman and the tea maker. But otherwise it depends on your degrees and experience."

Ironically, government welfare policy may have played a key role in the destruction of the tribal institutions of old Saudi society. A reflection of the old system is still seen in almost nightly television coverage of King Fahd, or others of the royal family, holding a majlis -- an open reception where citizens present requests and complaints -- and greeting the bearded tribal sheiks and ulema, or religious leaders, of the kingdom.

Masri points to the devastating "unintended effects" of the kingdom's generous home-loan policy. Under it, the state gave any Saudi an interest-free, 25-year loan of nearly $100,000 to build a home, and often provided the land. Masri estimates that nearly 1 million Saudis took advantage of this policy.

"It rang the death knell to a great heritage of Saudi society: the tribe and extended family," he said. "It created a suburban style of living where parents don't live with the children any longer."

Saudi Arabia now has suburban sprawls that have grown up around its old walled towns, bringing the tribal nomads into the heart of the Saudi state. Riyadh and Jeddah, which together had about 300,000 people in the late 1960s, today have 1.5 million -- and keep on growing.

Both have dozens of American-style suburban shopping centers, food store chains, flashy international hotels and public buildings in ultramodern architecture.

In many ways, Saudi society today seems uprooted and lonely, with one out of three persons in the kingdom a foreigner.

A young Saudi manager of a new petrochemical plant in Jubail remarked, "You know, I don't even know our neighbors living on either side of us except to nod when I come or go from the house." His own family is scattered, living in Riyadh, Mecca, the Eastern Province and Bahrain.

The new-found wealth of the ordinary Saudi can be seen in the suburban sprawl and in the enormous number of cars. A study by the King Abdul Aziz University found Saudi families, which average about six persons, have an average 4.8 cars.

It is the continuation of this bountiful, easy life that is at stake as the government cuts back on its $3 billion in subsidies for basic commodities, its easy loan policy and its practice of assuring shareholders in state-regulated companies a 15 percent profit. Already the prices of gasoline, electricity and some basic foods have shot up. Gasoline went up 70 percent last April, to $1.85 a gallon; electricity rates increased between 42 and 114 percent, depending on the amount used, and milk subsidies were ended. The price of cooking oil rose from 65 cents to $1.50 a pound.

Many Saudi intellectuals and officials see in the new "austerity" a healthy challenge to the care-free attitude of Saudi youth. Students, according to Masri and Deputy Education Minister Abdurrahman Subaili, are becoming more serious about their work and concerned about jobs.

Saudis, said Abdallah Dabbagh, secretary general of the Council of Saudi Chambers of Commerce, are discovering not everyone can, or ought to, become a businessman. The pressure, he said, is producing a "much more efficient and competitive economy." A farm manager said he was getting many more applications today than a year ago from Saudis now willing to take a job even out in the boondocks.

Politics in the kingdom, meanwhile, has become much more complex with the creation of powerful ministries, a huge bureaucracy and interest groups.

While the king is the supreme ruler, and relies heavily on consultations with others in the royal family, the Cabinet, although headed by either the king or crown prince, often acts as a decision-making center in its own right.

There are other "power centers" outside the royal family. One is the powerful 25-man council of the ulema, the religious leaders of Saudi Arabia's strict Wahhabi sect of Sunni Islam. Led by Sheik Abdulaziz ibn Baz, it is increasingly making its influence felt on daily public life and mores.

The ulema's influence with Fahd has grown since Iran's Islamic revolution, which has brought the House of Saud under enormous pressure, both religious and political.

Numbering at least 10,000, the ulema enforces a rigid public morality through religious police aided recently by the Interior Ministry's special morals squad.

In the past two years, the Saudi religious establishment has succeeded in reinforcing the segregation of women in work and public places, getting pinball arcades closed and seizing video films shown at international hotels.

A third power center is the military. Fouad Farsy, deputy minister of information and author of a book on Saudi Arabia, lists the military as the third most important element in the kingdom's government after the royal family and the ulema. It spends a third of the budget and builds its own separate "cities."

There is no doubt about the political weight of the 51,000-man Saudi armed forces and the 25,000-strong National Guard. The guard is under Crown Prince Abdullah, and the armed forces are under Defense Minister Prince Sultan, second in line to the throne. This high-powered leadership gives the military enormous clout in the infighting over the budget.

The fourth power center is the business community, which plays an essential role in consolidating support of the middle class for the royal family and kingdom.

The Chamber of Commerce's Dabbagh estimated that about 100,000 businessmen are registered with his organization around the country.

Based in a mammoth marble-and-glass edifice in Riyadh, the Council of Saudi Chambers of Commerce and Industry increasingly functions as a western-style lobby with the government.

One of the chambers' most important gains was a royal decree that all foreign contractors and joint ventures must set aside at least 30 percent of their work for Saudi-owned firms.

They also pressured the government into adopting the practice of subdividing billion-dollar contracts into smaller ones on which Saudi firms could bid.

The Chambers of Commerce council also is the only major organization in the country to elect its officers. Two-thirds of its governing board are elected by the membership and the rest are appointed by the Ministry of Commerce.

Fahd increasingly finds himself beset by the conflicting demands of these groups and called upon to decide in favor of one against the other, a radical change from the old days when there was enough money and contracts for all.

Several recent clashes over public policies illustrate the conflicting approaches within the government.

The most publicized incident involved Ghazi Gosaibi, a popular minister of industry for a decade and then health minister until he was fired last April. Gosaibi was a prime mover in the Saudi industrialization policy now coming to fruition and a hero of the commoners because he was leading a crusade against corruption, initially at the king's behest.

Gosaibi had been cleaning up the hospitals, firing administrators for bad management and embezzlement, when he clashed with a favorite of the royal family, Nizar Fetaih, head of the King Faisal Specialist Hospital in Riyadh.

Gosaibi tried to bring the hospital, largely reserved for the royal family, under his ministry's control and to fire Fetaih for mismanagement. In a showdown, Fahd sided with Fetaih and admonished Gosaibi for overzealousness.

Feeling his mission undermined and his favor with the king fading, Gosaibi took the unusual step of publishing a poem in a Riyadh newspaper that, in classical Arabic style, complained that the monarch was distancing himself from Gosaibi and listening to "a thousand slanderers" against him.

Gosaibi was fired and sent into political exile as ambassador to Bahrain, but the king apparently has belatedly conceded Gosaibi was right about Fetaih. He was fired last month and replaced by a three-man team.

Another such dispute arose in April 1983, when Prince Sultan, the defense minister, extended the contract of the U.S. Whittaker Corp. for management of Army hospitals until August 1986 without putting it to public bids. The new contract, for $2.2 billion, was to cover five hospitals instead of the original three.

A month later, the government decided all contracts should be put to bids and awarded to the lowest bidder.

Despite Sultan's support, Whittaker was told in December 1983 that its contract was terminated and it would have to compete with others in the public bidding. Whittaker rebid the contract for $1.1 billion but lost out to two other firms, one American and the other British, which agreed to run the five hospitals for about $435 million, according to U.S. sources.

While the Whittaker case ended with the Cabinet showing its teeth and voting down a senior prince, the outcome is not always the same.

Last June, Saudia, the state-run Saudi airline, bought 10 Boeing 747s on behalf of the Defense Ministry for reasons still obscure, since there was no evidence of a need for so many.

The ministry said it wanted them for carrying troops in case of an emergency within the country. But it already has more than 60 C130 transports, and outside analysts have questioned using jumbo jets for two-hour flights -- the longest possible within the kingdom.

Sultan arranged to finance the $1 billion deal outside normal treasury channels. He immediately ordered the Petroleum Ministry to sell 36 million barrels of oil.

In a move that raised more questions in international oil circles, the oil was sold in July, although the delivery date for the first planes is not until late 1985. There is widespread belief here that this was done to satisfy the financial wants of an important clan within the royal family.

The deal, which went against Saudi Arabia's longstanding policy against barter transactions in the oil industry and put further downward pressure on world oil prices, is said here to have been resisted by the Saudi oil minister, Ahmed Zaki Yamani. He was left with the embarrassing task of defending to colleagues in the Organization of Petroleum Exporting Countries a major switch in Saudi policy.

Western analysts here expect to see such tugging and hauling between commoners and princes in the Cabinet to continue over the use of Saudi Arabia's dwindling oil income. There is speculation that Gosaibi many not be the only commoner to go.

These disputes point up the atmosphere of uncertainty in the Saudi capital these days, reflected in the reluctance of many ministers to discuss, on the record, the country's prospects. There is a sense here of the government holding its breath and waiting to see what the oil market, so favorable to Saudi Arabia for so long, holds in store for the next decade.