When Clarence M. Pendleton Jr. was thumbing through a history book not long ago, he discovered the story of Nigger Add, a 19th-century cowboy described as one of the best along the Pecos River.

So out of the badlands of an old Texas and New Mexico, the beleaguered chairman of the U.S. Commission on Civil Rights plucked a hero. There's an easy physical similarity. The Dictionary of Negro Biography describes Add as "stocky and strongly built, with such powerful hands that he reputedly could 'practically twist the hide off' a horse." Pendleton, barrel-chested and mildly bombastic, tells the story of Add with all the star-struck exclamations of a kid describing Superman. "He wasn't supposed to be a cowboy. But all those white folks had to respect him for his ability. He is my hero just because he was self-sufficient," says Pendleton.

Survival, with a megadose of self-sufficiency, is what Pendleton, the most visible black appointee of President Reagan, is practicing these days. The calls for his resignation are mounting.

"I can't afford to get mad. I have to get things straightened out," Pendleton said the other day.

Has he thought of resigning?

"Never."

While accusations concerning Pendleton's leadership and financial dealings are surfacing, he takes solace in nods from the untitled -- an ice cream man in downtown Washington -- and the powerful. "Strom Thurmond said to me, 'You are one of the bravest men I know, and you do a hell of a good job.' He said, 'You have to do what you think is right.' And I am not going to let anybody run me out of this with innuendo and deliberate distortions of the facts," Pendleton said.

After months of relative quiet following his abrasive attacks on black leadership and a flurry of anti-Pendleton editorial replies, Pendleton is back in the hot seat. Last week John Bunzel, a Democratic commissioner and Pendleton ally, asked for his resignation, charging the chairman's "inflammatory rhetoric" had "undermined the credibility" of the group.

A few days later a group of black and Hispanic Republicans called on him to resign, citing his opposition to laws guaranteeing minority businesses a share of government contracts. "He has lost whatever usefulness he had," said Robert Brown, a businessman and former special assistant in the Nixon White House.

The General Accounting Office, requested by four congressmen to investigate the commission, concluded last month that mismanagement was rife and that Pendleton had turned his part-time chairmanship into a full-time job. He billed the commission last year, according to the GAO, for $67,344 in salary and nearly $30,000 in travel, far more than any other member of the commission. Tomorrow Pendleton is scheduled to answer a congressional panel's questions about the GAO findings.

The Small Business Administration and the California state's attorney's office, meanwhile, are investigating Pendleton business dealings in San Diego. Even the comic strip "Doonesbury" has been down on him, listing him recently among the "sleazeballs" of the Reagan administration.

"Lies, all lies," Pendleton said the other day. "As much in the public eye as I am, I would be a fool to do something wrong."

Pendleton, 55, is a product of the best of what black Washington had to offer its brightest in the 1950s. Those who knew him from the Deanwood and Howard University neighborhoods where he grew up, the old Dunbar High School or Howard, both of which he attended, usually just sigh at what they call the "new Penny." They wonder what has led him to articulate policies and principles many women, blacks and Hispanics think are designed to alienate, if not insult, them.

For long before the recent questions about his financial dealings, Pendleton dismayed traditionalists in the black community by challenging with other black conservatives the very assumptions on which the Civil Rights Commission was created.

"It has taken me four years to get to the right question that I think is on people's lips now: Is preferential treatment needed 20 years after the Civil Rights Act has been implemented? That is the number one civil rights question. If you give preferential treatment, does it eliminate discrimination or does it create more?" Pendleton asks.

"Can Penny really believe this stuff? Well, my view is yes," says Elias Blake Jr., president of Clark College in Atlanta and a friend since he and Pendleton taught at Howard. "I cannot conceive of Penny playing some kind of game at these high stakes. He is bright, able enough to understand what he is saying. He has a different vision of what our experience has been and feels we have to find a different way now. He really believes that. Now, I think he is totally wrong."

Pendleton's supporters see him following the new light, discarding outworn interpretations of equity in an effort to define the meatier civil rights battles of the next decade. But he remains haunted by charges that he gives comfort to conservative groups looking for reasons to hobble black progress.

"I don't like being called a lackey or an Uncle Tom," says Pendleton. "Bigots shouldn't find any comfort in what I say. I am on their case."

Pendleton, who is the first black to head the commission, has accused civil rights leaders of steering black Americans into a "political Jonestown"; tagged comparable worth "probably the looniest idea since Looney Tunes"; and labeled affirmative action "immoral." Says Pendleton, "I make no apologies for those. I think they make the point."

In return, The Atlanta Constitution tagged him the "Secretary of Social Misconceptions." The Detroit Free Press did a cartoon takeoff on "Looney Tunes," with a Porky Pendleton peeking out of the rainbow with a list labeled "No Civil Rights" and saying, "That's all, folks!" Such rejoinders, Pendleton says, "say more about them than they say about me." The Pendleton Puzzle

All his life, it seems, Pendleton has stood out from the crowd.

"What you see now is the same Penny as when he was 10 years old. He has always been a loner, always taken the opposite point of view," says Willie L. Leftwitch Jr., a local attorney and a Republican. "There was a Safeway right there and Penny didn't carry groceries like some of the other kids to earn money. But on Saturday at 5 p.m., he would come over to the Safeway and provoke a fight between two other people. He's always been a provocateur."

At other times Pendleton seems to have blended right in. "I had no idea he harbored these ideas," says Vernon Jordan, the Washington attorney who headed the national Urban League when Pendleton headed the San Diego branch from 1975 to 1982. "But I would defend any man's right to be a fool."

Some black Republicans faithful to the GOP for years look upon Pendleton as a political Johnny-come-lately: He was a Democrat until 1976. And their tolerance has run out. The other day one said, "It's him or us." Some share his frustration with the traditional civil rights leadership but object to his rhetorical flamboyance.

"As a black Republican, you get tired of always being characterized as a used-car salesman. Unless you come out of the civil rights bag, the civil rights people don't want you," says one. But he says few want to be aligned with Pendleton, whom he characterized as "without substance."

Still others are firmly in his camp. "What Pendleton has done is say bluntly and in capsule form things people are saying like myself," says Clarence Thomas, chairman of the Equal Employment Opportunity Commission. "Being out here, I know it hurts. The man has taken a pounding."

Pendleton knows his statements sound outrageous but believes he has made a point. "If I had not said what I said the way I said it, I would not have changed the debate." Due to the nature of his speeches, he says, "there has been more discussion about black politics and about comparable worth."

And he says that the ideas he shares with other independent black voices are gathering steam. "I read [Virginia Lt. Gov.] Doug Wilder's speech, and he sounds just like me. Glenn Loury [a political economist] sounds just like me, Bob Woodson [president of the Center for Neighborhood Enterprise] sounds just like me. I just sound like [economists] Tom Sowell and Walter Williams. Clarence Thomas and I sound alike, Brad [William Bradford Reynolds, the assistant attorney general] and I sound alike. What is going on? Why am I the whipping boy?" The Pendleton Debate

Right from his confirmation hearing in 1982 the Pendleton critics formed a line to the left.

The NAACP opposed his confirmation, later led the fight to have the commission reconstituted under Congress instead of the executive branch, and has opposed its renewal at every budget season. "Mr. Pendleton is misguided," says Althea T. L. Simmons, the director of the NAACP Washington bureau.

Pendleton believes government involvement holds back black progress, that legislation designed to help people out of poverty actually imprisons blacks, that the private sector is the key to black economic power.

Preferential treatment, he says, has created a new racism that blacks and whites perpetuate. "It is perpetuated further," he says, "when Congress wants to give preferences instead of allowing people to compete."

Many of Pendleton's critics, who believe the Pendleton commission has become ineffective, concede that some of his positions may be worthy of debate. But they charge that his rhetoric and his attacks on black leaders have closed the door. Says J. Clay Smith, a law professor at Howard and former acting chairman of the Equal Employment Opportunity Commission, who is a Republican, "He has exceeded the bounds of his public charge by baiting black leaders." The Pendleton Beginnings

"When I was a kid, your mother couldn't try on clothes at Garfinckel's. She could probably try on a little something at Lansburgh's. You couldn't sit down at the lunch counter in the 5-and-10-cent store or the department store. You could stand up at the end."

It was in Washington, in schools and church -- he was an altar boy at St. Luke's Episcopal Church for 15 years -- that he had a firsthand look at black leadership. His personal list of people with leadership qualities includes his parents Edna and Clarence, who coached swimming at Howard, his athletic coaches, philosopher Alain Locke, civil rights leader Martin Luther King Jr. and abolitionist Frederick Douglass, as well as politicians Reagan, Nixon, John Kennedy and Jesse Jackson.

He talks with great pride of Mary Church Terrell and others picketing the Peoples Drug Store at 14th Street and New York Avenue in 1951, demanding an end to lunch-counter segregation. He waxes eloquent about the solidarity of the 1963 March on Washington. But at the same time that he reflects positively on those days, he believes integration "killed our own black business areas, because we left them. We killed the dream we said we had to have. White folks didn't kill it."

Peola Spurlock Dews, who remembers Pendleton at Dunbar, says, "He is exactly the same, an individualist in his thought process. We were taught we were better than white folks. So we were arrogant and we knew we were going to make it. I heard someone call him an Uncle Tom. And I thought how tragic, because underneath he is saying, 'Let's get it for ourselves,' " says Dews.

But another classmate, George Dines, associate administrator of the federal Office of International Health Affairs, expresses a more common reaction: "I am a bit surprised at the new Clarence Pendleton. At Dunbar they instilled in us a sense of responsibility, to ourselves, to our families and then to society. Clarence has veered from all that. We were taught we are all out here together. That is something Clarence lost."

Yet in private and public forums Pendleton does reach back to the heroes of his youth to illustrate his argument for competition over preferential treatment.

"Charles Drew discovered how to separate and preserve blood plasma because he was talented," says Pendleton, who was born in Louisville but moved to Washington very early. "We don't have to be affirmative action candidates to succeed."

Pendleton represented the third generation of his family to attend Howard, which in those days was a standard-bearer for excellence and a catalyst for change. As an undergraduate, he played varsity football, captained the swimming team and joined Alpha Phi Alpha fraternity.

He finished Howard in 1954, spent three years in the Army, and then returned to Howard to teach physical education, coach the swimming team and earn a master's degree in 1962. The team, Penny's Sharks, won 10 championships in 11 years. "Penny was strong on keeping training, a good disciplinarian and a good motivator . . . . He has always believed in the individual achieving," says Togo West, a Washington attorney and former Shark.

At that time Pendleton had a personal mission, a friend recalls, to raise the visibility of blacks in sports like swimming, crew and wrestling. "There were some people who thought that was insignificant; people would say, 'Man, we are concerned about the revolution.' But Penny held his own. He felt we should be able to do all sorts of things," recalls Elias Blake. The Pendleton Philosophy

It was after Pendleton left Washington in 1968 for a job as recreation coordinator of Model Cities projects in Baltimore that he began to question the effectiveness of government help.

"I was always concerned how that money coming from the government was going to stay in communities," he said. "The biggest expense of most of these programs turned out to be the salary of the workers, not the products of the program."

In San Diego, where he first worked for Model Cities and then the Urban League, Pendleton earned the respect of the white power structure, including then-California attorney Edwin Meese (now U.S. attorney general) and then-San Diego Mayor Pete Wilson (now a republican senator from California). But his views and actions began to trouble some black leaders.

Clifford Graves, the former chief administrative officer of San Diego County and a friend of Pendleton, remembers "a shooting incident in downtown San Diego, a black youth shot by a white policeman. Pendleton may have been the only black who came out for support of the white policeman."

At the end of his tenure at the Urban League, he called himself the "most hated" black leader in the city, and to this day, one of his best remembered remarks was that "the best way to help poor folks is not to be one."

By then, Pendleton boasted that the profit-making real estate corporation he started was worth more than $120 million and had created 10,000 jobs. But he was criticized for almost bankrupting the league with his own expense accounts and leaving the organization heavily in debt. There were also several investigations into his management of $94,000 of a federal grant. He and the league board settled out of court. But now other deals from those years are being examined.

In 1980 he was the only Urban League director to support Ronald Reagan, and his handling of subsequent criticism appealed to the Reagan team.

At first, Pendleton says, he was leery of taking the civil rights job. His business success had whetted his appetite for other jobs. "You say . . . I want the Overseas Development Corporation . . . I want to get out here and find out how white folks make money, and bring that back to this community."

But he took the commission job, and right from the start he advocated ending the commission, drawing further fire from those who should have been his natural allies.

In 1976 Pendleton had a heart attack. He has built up his stamina since by running on the beach at La Jolla, where he lives with his second wife Margrit and Paula, their 6-year-old. Pendleton has two children by his first marriage, George, 26, and Susan, 22. He says his wife has felt the pressure from this recent round of criticism more than he has.

So, does the chairman ever think about slowing down, becoming a bit more cautious to ease the family strain and preserve a place for himself in the corporate or political world after his term at the commission? "I cannot caution myself," he says. "Am I sacrificing myself? I don't know."