In his spotless tennis whites and expensive leather shoes, a $100 racket tucked under his arm, Ray Carter is the picture of comfortable entrenchment in a sport historically reserved for the white country club set.

As a black teen-ager in Prince George's County, he preferred football and basketball, as did most of his friends. Now, at 25, Carter spends much of his money on tennis and most of his free time on the courts.

"There's twice as many blacks playing tennis as there used to be when I was playing in high school," he says.

Blacks such as Carter have moved to the Washington suburbs in increasingly large numbers since 1970, particularly to Prince George's, where housing is relatively inexpensive. Of the 11,000 black households that moved from Washington to the suburbs in 1977, the latest year for which data is available, 81 percent moved to Prince George's, according to Washington demographer George Grier.

Until recently, however, these blacks continued to look to the District for their jobs, their politics and their social life. But that is changing, say those who have studied the phenomenon, as blacks grow in number in towns such as Cheverly, Kettering and Upper Marlboro and feel more comfortable in their neighborhoods.

The most telling sign of their acclimation to the suburbs may be on the tennis courts, golf links and other scenes of participatory sports.

On a recent weekend, Carter, a Lanham resident studying to be a certified public accountant, was one of 18 blacks to enter the Southern Maryland Adult Open Tennis Tournament in Prince George's County. Until recently, the event drew a small number of black players. But this year, blacks made up about 36 percent of the field, a proportion only slightly less than the proportion of black population in the county, 37.3 percent.

Tennis tournament director Bob Lowe says the percentage of black players in suburban tournaments has grown from less than 10 percent to often more than 50 percent over the 14 years he has run such events for the Maryland National Capital Park and Planning Commission.

In contrast, the District for years has boasted excellent black tennis players who dominate the local rankings. The city's public tennis courts have been a haven for young blacks who are interested in the sport, and many have risen to be successful collegiate and tournament players. One District native, Rodney Harmon, is a national collegiate star and is currently among the best players on the professional tennis circuit.

Maryland state Sen. Decatur W. Trotter (D-P.G.) said he suspects the rising popularity of tennis among suburban blacks has been matched by a similar growth in the popularity of golf. Trotter is sponsoring a fraternity golf tournament at Largo's Newbridge Country Club in September -- a tournament he said would not have been possible 10 years ago because there would not have been enough players among his black fraternity brothers.

"More blacks are interested than ever before," says Trotter, who also exercises by swimming laps in his backyard pool in Glenarden. "We see blacks on the pro tour; fellows get more interested when they see one of their own."

Trotter took up golf a decade ago when he was mayor of Glenarden. Learning the game became a "political necessity," he says, when he discovered that the golf course was often the best place to talk to other politicians.

The son of a teacher and a Navy mechanic, he is the first in his family to play golf. His father worked odd jobs at night and his mother was busy with her children. "There wasn't a whole lot of time for them to put into golf or bowling. We just have a lot more leisure time," he says.

As Trotter indicates, suburban blacks have gotten increasingly better jobs and thus more income to spend on sports than have their counterparts in the city. The average income of the 15,000 black households that moved to Prince George's between 1975 and 1980 was $21,000, slightly above the average income of $20,700 for all District households during those years, according to an analysis of census data by Grier.

Blacks, like whites, have easier access to golf courses in the suburbs, Trotter says.

Bart Landry, a University of Maryland sociologist who has studied black suburbanization, agrees. "There are simply more apartment-complex swimming pools and community recreation facilities in the suburbs," he says. Suburban schools, he adds, often have more space than urban schools and are therefore more likely to offer extracurricular activities such as soccer and tennis and sports facilities to students and the community.

Moreover, in the suburbs "it's easier to get around to a lot of things. You develop a life style around a car," he says.

Ernest R. Myers, professor at the University of the District of Columbia who also is conducting a study on middle-class blacks, agrees that locality is an important factor in choosing how to spend leisure time.

"When people live closer to a bowling alley, they bowl more," he says. "When they move close to a tennis court, they may peek in and give it the old college try."

Running, a sport in which blacks traditionally have excelled, does not appear to have caught on as much as tennis and golf among black suburbanites, race organizers say. Although the percentage of blacks participating in community-sponsored races has increased over the past few years, the number of black runners remains low, especially in the suburbs.

Ed Bowie, who runs a track program for the bicounty Park and Planning Commission and coaches track at Central High School, says more blacks are running for exercise and competing widely in traditional short-distance track events but are not represented as well in long-distance races.

"The jogging movement is not an overly competitive thing," says Bowie. "It could be that black athletes are more highly motivated competitively."

Myers' research on middle-class blacks has shown that young blacks often look to their leisure activities to make professional as well as social contacts, perhaps more so than do whites. Many tackle their activities with a ferocity that suggests they are still not wholly comfortable in their new roles. They must live up to standards by which they believe they are being measured, says Landry.

"Black suburbanites . . . are often moving where they'll be very visible," he said. They may be "anxious to do the right thing, to prove they made it, to prove they belong."

Wilbert R. Wilson, director of a minority trade association who was an aide to former county executive Lawrence Hogan, preaches to young blacks that "if they really want to move ahead in society" they should learn tennis and golf.

"The name of the game in society if you want to be successful is to be well-rounded," he says. "We're teaching that young blacks must play golf and tennis, those two are status things. More deals and more friendships come off the golf course." Wilson travels around the country with other black golfers to play in benefit tournaments and speak to young blacks about taking up the game.

Wilson, 39 and a Mitchellville resident, grew up poor in Lynchburg, Va., as one of nine children. He learned to play golf while caddying at a white country club.

"Had I been granted the opportunity when I was a little boy to participate on an equal level, no doubt about it, I would have been a pro," he said.

"In the last four or five years, I've really seen a surge in black golfers, from teachers to truck drivers to bricklayers to gas station attendants. Golf is no longer an illustrious group of people. It's really an everybody's sport."

Not everyone has noticed the upswing in middle-class black sports enthusiasts. Health club owner George McDermott says he had trouble persuading banks to back his Washington Racquet and Fitness Club, which opened two years ago in Silver Hill. "The banks told me that blacks don't play racquetball," McDermott says. "They said it would flop."

But the owners say that 75 percent of their 3,000 current members are black. "Blacks do play racquetball," McDermott's wife, Patricia, said.

Blacks also ski, proven by the success of Black Ski, a Washington-area club with about 300 active skiers. Dee Wilson, a Largo resident and member of the group, is among the estimated 40 percent of the group's membership living in the suburbs.

Wilson, 47, divorced and a specialist at the Social Security Administration, moved to Seat Pleasant 15 years ago in search of an acceptable apartment that would take children. She has since moved to a Largo apartment complex, which she chose because it had a tennis court.

When blacks take up skiing, they often spend more than whites, says Pam Taylor, an officer of Black Ski.

"Blacks, unlike whites, are not comfortable putting on jeans and Scotchguarding them," she says. "When blacks get involved in something, they get involved in a big way. They buy the best equipment and they buy the best clothing."

Wilson spends between $2,000 and $3,000 a year on the sport, and she has been skiing for 10 years. Initially, she said, she resisted learning to ski. But social changes, including the women's movement, have affected her life style.

"I'm a child of the fifties, and girls only did certain things," she says. "I thought I'd get hurt. I thought I'd freeze to death.