Twas six nights before Christmas, but it could have been any evening of any season. Fifteen-year-old Steve Rader was well into the eighth hour of his typical 10-hour day at Wheaton Plaza, the shopping center he calls "more home than home."

Four of those eight hours had been spent as an after-school counterman at the Orange Bowl, a pizza parlor. One hour had been spent "checking out records and girls," not necessarily in that order, at Variety Records. The last three had been spent feeding quarters into a flashing, screeching game called Alien Poker, at Time-Out, a video games emporium.

Nor was Steve Rader's day at Wheaton Plaza close to being finished. "Oh, I'll be here maybe another two hours or so, until it's time to go home, get something to eat and go to sleep," said Rader, a sophomore at Einstein High School.

Is this how he spends most days? "Let me put it this way," Rader said. "I definitely plan to be here tomorrow after school, for most of the day. And the day after that. And the day after that.

"See, I know Paul Quinn over there, and Chip Johnson down there. This is like a community of friends for me. This is where I feel comfortable."

Twenty-one-year-old Wheaton Plaza is certainly not the only shopping center in the Washington area whose central location and youth-oriented stores have turned it into a mecca for teen-agers.

But as the oldest major shopping center in Montgomery County, going to Wheaton Plaza has been a habit for two generations of county teen-agers -- some of whom are now parents of the current crop. In addition, the plaza is one of only a handful of regional shopping centers in the Washington area whose teen-age regulars live close enough to walk there rather than drive.

Indeed, Wheaton Plaza is trying so hard to make a good impression on teen-agers that graffiti relating to any nearby high school is routinely painted over in the restrooms of the Hot Shoppes cafeteria. Some merchants offer half-price sales to those celebrating their sweet 16th birthdays. And the canned music billowing out of the loudspeakers in the mall is Elton John and Donna Summer, never Mantovani.

Says Paul Quinn, a 33-year-old Montgomery County policeman who himself grew up less than a mile away from Wheaton Plaza and who moonlights as a security guard at Time-Out:

"This plaza is the ball field and the dance hall and the Saturday night date I used to know all rolled into one . . . (It's) a neighborhood center for neighborhood kids, almost a neighborhood itself."

Statistics developed by an investment analyst familiar with Washington-area shopping centers bear out Quinn's observation.

According to the analyst, although Wheaton Plaza's adult trade comes from "all over -- Kensington, Rockville, Silver Spring, Northwest Washington, you name it," at least 60 percent of its "youth business" comes from Arcola, Kensington View, Glen Haven and College View -- all middle-class subdivisions within a mile of the main entrance at University Boulevard and Veirs Mill Road.

"The kids all know each other from Wheaton and Einstein and Good Counsel (high schools), and they walk to the plaza," the analyst said. "It becomes a kind of community center, a place to hang around until mom gets home from work. You don't see as much of that at, say, White Flint, even though there are so many more places to eat there or just to sit down."

However, serving as a "teen-agers' neighborhood" is not all peaches and cream for Wheaton Plaza.

According to Montgomery County police, the plaza's Lot 19 -- a parking area along the northwestern edge of the shopping center -- is notorious as a nighttime gathering place for young drinkers, or vandals, or both.

"You say Lot 19 around the plaza, and everyone knows what you mean," said Quinn. "A lot of mornings, you can go up there and see broken beer bottles about an inch deep from the night before. Then there's the fights, and the way they yell obscenities at cars passing by. And if you run them out of there, they just go someplace else."

However, Wheaton Plaza merchants have been determined to keep disorderly young people out of the mall itself -- and they say they have succeeded.

Time-Out spends $30,000 a year for security guards, according to Tom McAuliffe, its vice president for operations, "and we patrol all over, not just in front of our door, just so we can say that kids who frequent our place aren't causing trouble elsewhere in the plaza." Meanwhile, the plaza's own security force has been increased from four to six officers in the last two years.

"That arcade over there (in front of Time-Out) used to be much more of a hangout than it is now," said Joe Goldberg, owner of Variety Records and one of Wheaton Plaza's original shopkeepers. "But the security has gotten so good that now, if kids are driven away from there, they tend to leave the plaza entirely, not just move someplace else."

"Kids wouldn't be here if they didn't feel at home here," said Irvin Losman, whose family owns and operates Tiara Gifts and who is president of the merchants' association. "But this is no longer a hangout with all the negative connotations, if in fact it ever was."

Indeed, The Lerner Corporation, owner and operator of Wheaton Plaza, seems so enamored of young customers, and a youthful image, that it has taken two steps in the last six months to increase both.

Four former tenants, three of whom appealed mainly to an older clientele, have been replaced with a pastel-painted fast-food restaurant and three youth-oriented clothing stores.

Meanwhile, after what Losman describes as "20 years of rumors, hopes, debates and promises," Wheaton Plaza will soon become an enclosed mall in the manner of its chief competitors: Montgomery Mall, White Flint and the new Lakeforest Mall in Gaithersburg.

According to Max Ammerman, Wheaton Plaza's general counsel, the covering will be a translucent dome that will cost $5 million. "It should be in place 18 months from now," Ammerman said. "The tenants have always wanted it, and we want it. . . We're enthusiastic. Wheaton Plaza has been a viable shopping center for 21 years, and this should keep it that way for at least another 21."

Steve Rader says he does not know if he will still be spending so much time at Wheaton Plaza 21 years from now. But he says he wouldn't be surprised.

"The only thing that's free is sitting at home. . . Why should I want to do that when I'm older any more than I do now?"

Rader's friend, Chip Johnson, describes his fondness for the plaza another way: "Girls don't run through nobody's living room."

Alien Poker games don't, either.

"I got the high game here on that -- 1,260,000 points," Rader said, "and if that doesn't make me feel at home in Wheaton Plaza, nothing ever will."