REMEMBER THE COWSILLS? Sure you do: They were the original family of preteen pop idols, five moptopped brothers, a kid sister and a miniskirted mom, whose buoyant bubblegum songs "The Rain, the Park and Other Things," "We Can Fly," "Indian Lake" and "Hair" went to Number One. From 1967 to 1970, the Cowsills grinned wholesomely from lunchboxes and the covers of teen magazines. They did Vegas and TV specials and milk commercials. And they were the prototype for the "Partridge Family" TV series.

"Yeah, the people from Screen Gems even came and lived with us for a while," remembers Susan Cowsill, who was seven when she was drafted into her brothers' band along with her mother, Barbara.

The TV execs scoped the family out and liked what they saw as far as the kids were concerned. "But they could obviously see my mother's hesitancy, and so they wanted us to do it with Shirley Jones. But we wanted to do it with our mom, so we said they should go ahead and do it with actors.

"I always watched it, though, and I spent hours trying to figure out which one I was, praying to God it wasn't the little lobotomized one who, when she went to hit that tambourine totally missed it. And I personally thought David Cassidy was a much hipper big brother -- he didn't torture his sisters at all. I knew they didn't get that part from hanging around with us."

After 20 years of troubled post-teen times, the Cowsills have restored their family harmony and will appear Monday at the 9:30 club. Several reunion reports have called theirs a "riches-to rags" story.

"It's really rags-to-riches-to-rags," says Susan, now 30. "They left out one set of rags. Don't forget that we were just this hick family from Rhode Island. You can clearly see that in our photos from the early days, where I didn't even bother taking a shower and my cuffs and sleeves had dirt on them.

"Four of my brothers had a band -- everybody wanted to be the Beatles then," she remembers. "And my dad, who had been in the Navy for 20 years, apparently woke up one morning with this brilliant idea to stick my mother and myself in this band . . . .

"So we went from living in Rhode Island, burning our furniture for heat, to living in Brentwood {Calif.} and everybody's got bicycles and I have a dog and a trampoline. I was just a kid; I didn't see it quite for what it was. All I knew was wherever I went people were really happy to see me."

Things went fine -- the hits, eight albums, wide-scale teen idolatry, and the cash that went with it. But their father and manager, William "Bud" Cowsill, made some bad investments and filed bankruptcy in 1975.

"My dad did what he thought was the thing to do to take this thing where his children wanted it to go," Susan says. "And in my opinion -- in all of our opinion -- my father did a very good job with his 7th-grade education. We all made maybe not the correct decisions at the time."

The fall happened as quickly as the rise, and it was especially confusing to Susan, the youngest. "I was 13 and all of a sudden I was put into a public school and told to behave like everyone else, getting harrassed by kids who knew our band was over," she says.

After vanishing from the magazine covers, the post-adolescent Cowsills went through some bumpy times, including a spate of drug and alcohol problems. Their mother died of emphysema in 1985; the reformed group dedicated its first concert together, at Boston's Zanzibar club in July, to her memory. "Every family has its ups and downs; we've had ours too," Susan says.

The "core four," as they call themselves, include Susan, who sang backup on a couple Dwight Twilley records, and writes songs with her friend Vicki Peterson of the Bangles ("nothing anybody's heard -- we have a slumber party, eat popcorn and write"), on rhythm guitar; keyboardist Paul, 37, was Helen Reddy's road manager and is now a carpenter; John, 33, who has worked as a session drummer for Bob Dylan and Jan & Dean; and Bob, 39, on lead guitar, who has been performing solo in L.A. coffeehouses for years. Bob also writes and produces most of the new material, including a song called "Some Good Years," which Susan says is "about how as time goes on, the bad part seems to fade away."

Brothers Bill, 42, and Barry, 35, are sitting out the tour, but may join the clan later for recording, as will Richard, Bob's twin brother, who was arbitrarily excluded from the band the first time around by Bud Cowsill, who now lives in Mexico.

Susan says she and her brothers made a reunion attempt in 1978, and recorded several tracks that met with record company indifference. "The music situation was extremely defined at the time -- you had to be either disco or punk. So it didn't appear to be the right time for the Cowsills, and we put it to bed," she says.

Why it's happening for them now is "the influx of the '60s thing," she says. "But we didn't want to be just a band from the '60s touring around singing 'Hair,' although we love it and we do all our hits in our show. Good old rock 'n' roll music is popular again even with the new bands, and pop is back. So my brother John called about 10 months ago and said, 'Susan, let's just try it one more time.' "

The 14-track "Best of the Cowsills" is available on Polydor compact disc, and the group is currently shopping a tape of original material to labels. "Tom Petty meets Fleetwood Mac while visiting with the Pretenders while having the Byrds over for dinner" is how some people have described their sound.

"We respect and feel warmly toward our past. You have to put it in perspective -- without that early idolhood, nobody would be interested in who we are now. So we're presenting ourselves as a new band who also had some hits in the '60s, and sure, we'd love to play them for you."