The sea of prosperous white male faces, the paunches and the receding or vanished hairlines are signs that the American Bar Association, as represented by its 3,000 leaders who concluded their convention here today, still retains its image as quintessentially establshment.

The favorite word in debates is still "appropriate," the favorite preoccupation is still earning money and, it can be said, these lawyers will never be wild and crazy guys.

But slowly, with the utmost decorum, the world's largest voluntary professional organization, with a membership of 270,000, is changing. One of the noticeable characteristics of this change is the contrast between the ABA's past and its future.

Today, for example, the leaders nominated Jane Barrett, a Los Angeles attorney, to serve on the organization's board of governors -- the first woman to be nominated in ABA history. And Brooksley Landau, a woman attorney from Washington, now chairs the ABA's most prestigious committee, the one that screens federal judgeship nominees. She is also widely perceived as the first serious woman candidate, five or 10 years down the road, for ABA president.

But that is the future. Its past was exemplified two nights ago, with an incident at a cocktail party when a prominent male ABA member was asked his opinion about the political future of a prominent female member: within earshot of dozens of lawyers and reporterss, he belittled her sexual prowess.

On Saturday, the association denied a vote to the Misssouri state bar delegation because it did not include a member under the age of 35, in accordance with ABA rules. And at its last meeting, the association approved an affirmative action recommendation for law school admissions.

The association also served as a forum for pleas to save the Legal Services Corp., which funds legal aid for the poor, from the threat of extinction under the Reagan administration.

At the same time, however, the association made significant modification in a series of recommendations to improve the legal status of prisioners because of objections raised by corrections officials around the country. This was perceived as a setback for "liberal" activists in the ABA.

And though the ABA has approved affirmative action for law schools, blacks play no visible role in this organization. Saturday, without a real fight, the delegates deleted a recommendation that might have played an important role in helping blacks gain public office in all white city and county councils throughout the South.

The original resolution called for ABA approval of single-member districts for state legislatures and local governmental bodies around the country. Multi-member, particularly multi-member at-large districts, are currently thought by civil rights proponents to be responsible for the inability of blacks to hold elective office, even in some places where they constitute a third or more of the population.

The ABA House of Delegates struck that part of the resolution calling for single-member districts for local governmental bodies.

But no one whose memory goes back five to 15 years, when the ABA seemed almost exclusively preoccupied with professional self-preservation, thinks the ABA hasn't changed.

The election today by state delegates of official nominee to serve as ABA president in 1982, illustrates the change and its tentative pace.

In the '60s and much of the '70s, the choice of an ABA president -- who gets wide exposure and prestige as a spokesman for the legal profession -- was said to have been wrapped up months, even years in advance. Challenges to the accepted choice were rare, close races even rarer and the positions of potential presidents on issues confronting the country and the profession seemed irrelevant.

This year in Houston, there were three candidates and one of the closest races in years. Dallas lawyer Morris Harrell won on the fifth ballot by a single vote. He had entered the race for this year's selection just a few months ago, in contrast to his challengers, who have been campaigning for years with the Houston meeting in mind.

Each candidate this year was asked to provide position papers to the state delegates and to show up at a candidates forum. The first substantive question at that forum concerned their position on legal services for the poor. q

Nevertheless, their responses were as expected and hoped, not too warm but not too cold. It is now standard for ABA leaders to endorse the need for legal services at public expense.

Those selected as leaders continue to be identifed with corporate legal interests. Harrell, for example, is a member of a Dallas firm of about 40 lawyers largely concerned with business-related litigation.

Barrett, the first woman nominee to the board of governors, specializes in maritime and railroad legal interests. But her background is of a kind that would have undoubtedly excluded someone in year past. As a student at the University of Southern California, she helped organize protests to shut down the school for a day over the invasion of Cambodia.

And while some activist women lawyers privately wish that a more militant women's rights activist had emerged, Barett's expressed mission is appropriately in tune with the times. "The ABA cannot be an influential organization unless it represents the lawyers in this country," she said in an interview, "all the lawyers and that means women, blacks and Chicanos."

"It's a question," she added, "of the ABA making an affirmative attempt."