When Virginia Gov. Charles S. Robb took office four years ago, he told several acquaintances that his administration had a simple mission: Bring Virginia into the 20th century.

Robb, the son-in-law of President Lyndon B. Johnson, offered no master plan or "Great Society" for a state much in love with its conservative past. Yet Robb will leave office next week as a man who has changed the state's image and as one of Virginia's most popular governors.

Robb, 46, charted a course that combined elements of fiscal conservatism with a strong emphasis on social concerns, economic growth and a determined effort to erase entrenched racial attitudes that pervaded the state government since the Civil War. That image of a more moderate, racially sensitive southern state, some say, may be as enduring as any law or program Robb created during his four years in Richmond.

"I think he played a great role, basically because of his appointments and the way he handled people of all races," said state Sen.-elect Benjamin Lambert III of Richmond, one of many blacks who said Robb's greatest legacy may be the improved racial climate he fostered. "He gave people a sense that they could believe him and that he was a fair person. He could be trusted. He did it in a way that didn't get people upset."

As governor, Robb directed massive infusions of state money into public schools and demanded stricter standards for both pupils and teachers in return.

He gave minorities major roles in his administration and appointed hundreds of women and blacks to boards and commissions. He stopped a 25-year trend of increased growth in state regulation and growth of the state bureaucracy, leaving Richmond with 2,000 fewer employes on the state payroll than when he began.

"He's shaken up things," said Senate Majority Leader Hunter B. Andrews of Hampton, who used to deride Robb as "Chuckie Bird" when he arrived in Richmond eight years ago as lieutenant governor.

"He's made some social moves and changes that will inure to the benefit of the commonwealth . . . without upsetting the citizens," said House Speaker A.L. Philpott (D-Henry), a former segregationist and a pivotal Democratic leader of the conservative state legislature.

Unlike his recent Republican predecessors, Robb came into office with an agenda to change -- rather than manage -- the state government. He did that largely by installing professional administrators instead of retaining many of the political cronies -- the largely white good ol' boys, critics would say -- who had run Virginia for decades.

Robb, barred by law from succeeding himself as governor, refused to accept the excuses of tradition. Andrews, who traces his family to the state's colonial days, found himself applauding Robb for that. "He's certainly prone to ask 'Why?' and that's good," Andrews said.

Moreover, Robb pressed an aggressive agenda for affirmative action. He appointed the first black to the Virginia Supreme Court and later picked a woman for the State Corporation Commission, the powerful, quasi-independent regulatory agency.

Robb initiated such changes with little fanfare, a style and approach that he recently said allowed him to make substantive changes without excessively rousing critics or opposition throughout most of his term.

"We had an informal mandate to make the changes we saw necessary, as long as we did it in a rational manner and didn't create too much controversy," said Eva S. Teig, Robb's labor commissioner. "He's cautious in a good sense."

At the outset, Robb, a young Washington lawyer who lived in McLean, clearly had his critics. In 1977, liberal politician Henry E. Howell of Norfolk denounced him for having "parachuted in." Those comments reflected the widespread view of Virginia, once described by political scientist V.O. Key as a "political museum piece," in which politicians have to work their way up through the legislature or county courthouses.

Robb is one of the successful few who started at the top. "That doesn't give you an awful lot of experience," Philpott said in a interview. "A lot of people were having serious reservations . . . but it's obvious to all of us that Chuck Robb has been an excellent governor."

Despite widespread favorable impressions, the Robb administration also has faced failures and setbacks. Among them:

*Corrections -- Long-simmering problems in the prison system were aggravated by early Robb budget cutting and weak management that was exposed in May 1984 by the escape of six death row inmates from the Mecklenburg prison, the largest breakout from death row in U.S. history. Robb went through three corrections directors in three years and the system is only now beginning to emerge from the years of turmoil.

*Voting Rights -- Robb promised to ease restrictive registration regulations that had given the state one of the worst voting records in the nation, but he failed to push substantive changes through the General Assembly. It repeatedly killed proposals to allow registration by mail and other revisions Robb had favored.

"That's one of the big negatives of the Robb administration," said Danny LaBlanc, secretary-treasurer of the state AFL-CIO.

*Mental Health -- The state's sprawling mental health system remains snarled by policy disputes and entrenched bureaucratic interests, even though Robb briefly suspended his mental health director in 1984 and dispatched a management team to end the chaos.

*ERA -- Robb fought hard for the federal Equal Rights Amendment, but was unable to get the measure to the floor of the House of Delegates.

*Taxes -- While he kept his promise of no general tax increase, some taxes and fees for services increased. Robb retreated from his campaign suggestion that the state abolish the 4 percent sales tax on food and medicine.

*Higher Education -- While emphasizing elementary and secondary education, Robb feuded with presidents of major universities over high costs. And, despite funneling huge sums of new money into the overall educational system, educators say Robb failed to address fundamental problems faced by the state's 20-year-old community college system.

The governor's proposal that the federal courts end 16 years of jurisdiction over state efforts to desegregate its previously segregated colleges has yet to win support from the Reagan administration, although Robb is credited with doing more than any other recent governor on the issue.

Some smaller counties and rural areas have worried that Robb paid too little attention to agriculture, the state's biggest industry, while focusing on the urban corridor that stretches from Northern Virginia to Richmond and then to Norfolk. "I don't get the sense that he is all that sensitive to the needs of local areas, particularly rural area economic development," said one highly regarded lobbyist who asked not to be identified.

In some instances, the Robb administration made calculated decisions that some problems would have to wait for another governor.

Chief among those, the state's multibillion-dollar highway department, a powerful statewide and political bureaucracy largely unchanged in 40 years. Robb, who brought in a broad range of new agency heads, early in his term reappointed Commissioner Harold C. King, signaling no radical changes.

"One thing links all of those things," said Larry J. Sabato, a University of Virginia professor and student of Virginia politics. "Robb has not been a good hands-on governor," Sabato said, suggesting Robb views his job similarly to a chief executive officer who sets broad policy for others to carry out.

Sabato contrasted Robb with Gov.-elect Gerald L. Baliles, who Sabato said would involve himself more intimately with the operations of the government. "Robb does not have a fascination with how things work," Sabato said, just that they work.

"He delegates an enormous amount of the preliminary work," agreed George M. Stoddart, Robb's press secretary. Stoddart said Robb, who generally works from "morning, not early morning, to late at night" does extensive reading on a wide range of subjects. "He is very well schooled on these issues before they get to him . . . . He's incredibly well prepared."

The style meant that Robb may have appeared aloof to lower, mid-level bureaucrats, but he established clear-cut policies to follow, Stoddard said. "The genius behind his approach is to get the rest of the state government to go along . . . ," he said.

Admirers and critics alike tend to compare Robb's impact to only two other governors in this century -- Harry Flood Byrd Sr., whose late 1920s policies and political organzation guided the state for more than 40 years, and Mills E. Godwin, whose first term in the 1960s founded the community college system and established a state sales tax that helped move the state away from Byrd's fiscal straitjacket "pay-as-you-go" policies.

Robb quickly embarked on his plan to open up state government by naming more women and blacks to policy-making positions.

He delighted in meeting with conservative legislators who complained that Betty J. Diener, the "lady" Robb named as his secretary of commerce and economic development, had used vulgar language.

"Don't men swear?" Robb fired back. "I didn't hire her to be a lady; I hired her to be secretary of commerce."

In all, Robb named more than 900 women and blacks to state courts, boards and commissions -- effectively showing that Virginia's revered conservative government would not come tumbling down if white men did not control everything. Fifteen women were named department heads in a bureaucracy accustomed to being run by men.

"Everybody knew we weren't there just to fill up a quota," said Teig, secretary-designate of human resources under Baliles.

During his term, Robb, generally known for a cautious approach to major decisions, showed he could act dramatically when an opportunity arose, such as when the legislature deadlocked over vacancies on the Supreme Court and on the corporation commission. Robb picked a black Richmond lawyer, John Charles Thomas, for the court, and Elizabeth Lacy for the regulatory agency.

Thomas, a lawyer with the Richmond-based Hunton & Williams -- the same firm Robb will join this month -- was appointed in 1983. True to his style, Robb kept the decision quiet -- even Robb's chief of staff, David A. McCloud, did not know about it until the day before it was announced.

Before appointing Lacy, a former deputy state attorney general, earlier this year, Robb huddled with close advisers and said he was determined to appoint a qualified woman to a vacancy on the three-member SCC. It was a move designed to shake up the 82-year-old, all-white male institution that has been among the state's most controversial agencies in recent years because of utility rate cases.

The governor's own brand of affirmative action extended to state government purchasing. In the last year of Republican Gov. John N. Dalton's term, the state spent $260,000 with minority contractors, according to Robb's office. The state now spends about $36 million a year and keeps a list of minority firms that most state agencies must review before awarding contracts.

Robb's first executive order was to establish a state policy of equal employment and promotion opportunities, noted H. Benson Dendy III, a longtime Robb aide who was appointed secretary of the commonwealth this year.

Robb also is credited with committing the state to cleaning up the polluted Chesapeake Bay, championing the rights of the handicapped and boosting economic development and initiatives that enabled him to avoid general tax increases. In his January 1982 inaugural address, Robb reaffirmed campaign promises to make elementary and secondary education improvements the cornerstone of his administration.

"Nothing we do will be more important," Robb said then. "No other effort will have as profound and lasting an impact upon our future . . . the hour has come, the urgency is acute, for us to do whatever we must to reclaim for Virginia national preeminence in education."

Robb, who had campaigned on a pledge to make government more efficient and to avoid general tax increases, moved quickly to free more money for education by initiating a detailed review of the budget of each state agency, a plan that he called "level funding," and one designed to question every dollar spent by the state.

"He firmly believed that state government was fat and he squeezed it," said Philip Abraham, one of Robb's chief policy advisers. "That's how we were able to move forward in so many areas without a major tax increase."

Robb also was faced with a withering budget crunch brought on by the 1982 recession that drove down inflation -- effectively cutting out the spiraling growth of easy revenue that had financed most budget increases of recent administrations.

"It came during one of the worst periods of cutbacks and retrenchment at the federal level," Abraham said. Robb initiated cutbacks of about 12 1/2 percent or more during that period for most agencies, exempting only a few areas, such as schools. Family aid programs suffered from the twin assault of federal cutbacks and the limited willingness of either Robb or the legislature to take up the slack.

Under Robb, however, state aid to education flourished and a decade-old trend of decreasing state support was halted.

Per pupil spending rose in three years by more than $700 and, fueled by the economic turnaround, is expected to go higher in the two-year budget Robb will submit in January. "I think improvement in public education is a lasting accomplishment," said Senate Majority Leader Andrews.

"Financing elementary and secondary education has increased by more than $1 billion, with a considerable amount used to improve salary compensation of teachers," said Ralph Shotwell, chief researcher for the Virginia Education Association, an influential lobbying arm of state teachers and educators that was among early skeptics of Robb's intentions.

Robb's plans were hardly unique. Governors across the South have struggled in recent years to improve state education systems that, with the exception of booming suburban areas like Northern Virginia, traditionally lagged behind northern states.

In one of his most ambitious proposals, Robb pushed through a $30 million program to establish a Center for Innovative Technology in Northern Virginia, a research agency still being formed that is supposed to promote research at colleges as well as among high-technology industries.

The center, however, has had trouble publicly defining its mission to skeptical state legislators and has struggled with well-publicized administrative start-up problems that Robb and Baliles are still struggling to solve.

Far less publicity has been given to the administration's systematic review since 1982 of thousands of state government regulations, an effort Robb personally ranks as one of his most important continuing achievements.

Diener, secretary of commerce, said agencies under her alone reviewed more than 35,000 regulations, eliminating almost 7,000 of them and simplifying about 8,500.

"The agencies . . . weren't too thrilled about it," Robb adviser Abraham said. "Previous efforts by other governors were seen as trying to impose from above. We approached it in a different way."

Robb met with agency heads and explained what he wanted, Abraham said, but left it up to the agencies and a task force of business, labor, government and consumer groups to work out the details.

The changes, generally endorsed by all of the groups, "will have as long lasting effect as . . . public education and economic development," Abraham said. "I'd rank it up there with those."

Two key changes require that proposed regulations be published for public comment in a new Virginia Register and that new regulations be approved by the governor. Legislation scheduled to be introduced in January would require that all occupational and health regulatory boards include at least two citizen members.Next: Robb, the politician.