There was no "gala" dinner-dance in a fancy ballroom for The Jewish Congregation of San Geronimo Valley's 10th anniversary celebration. Though its steady growth and longevity is no small feat, considering the group's semi-rural location in bucolic West Marin, members opted to mark the milestone on Dec. 29 in typical style — with a "family party" and tribute to founder Suzanne Sadowsky at the local community center. About 70 attended, and no doubt anyone who wanted to speak up, did.

"It's really participatory and egalitarian," board President Andreas Wittenstein says of the congregation, which has approximately 65 dues-paying member households and 40-some children attending its Sunday school. "And it's really haimish, a family atmosphere."

Last fall's High Holy Day services drew close to 100 men, women and children to the San Geronimo Valley Cultural Center. At Yom Kippur, with guest Cantor Armin Rosencranz leading services, Wittenstein performed a cello meditation, Talia Rose played the harp, readings went round the room and Andy Radar told a mesmerizing parable. Sadowsky delivered the drash — a political commentary of sorts, which sparked a lively debate when a few spoke up to contest her slant in the retelling of a news story. Any ruffled feathers, however, were smoothed over before the Torah service came to a warm conclusion.

The mini-debate was not unusual in this group. "It's an eclectic mix, it's hard to get people to agree on anything," says Wittenstein, who joined up about five years ago after trying just about every other established congregation in Marin.

Davo Knepler, who attended the first exploratory meeting at Sadowsky's home after seeing her ad in valley residents' local newsletter, "Stone Soup," recalls some of the earliest discussions.

"For many years, it was a congregation by geography — the link being that people lived in the valley and were Jewish," Knepler said. "Some of our earliest debates were over the word 'congregation,' because it pressed buttons for some people.

"They felt comfortable socially, but mixed about connecting religiously."

Knepler, who grew up in a Conservative household in Connecticut and whose parents helped start a shul there, characterized himself and fellow Woodacre resident Michael Chadwick, another original member, as "two of the more religious veterans" in the group. As such, they've been called on to assist with many of the "religious aspects" of the lay-led group, such as Friday-night services. Knepler, who has two young children with his wife Karin Koenig, also helped begin the Penina Maier Children's School, which now supports five classes. As "pseudo-director" of the school, Knepler sees its evolution as "an indication of how the congregation has changed" from its earliest anti-establishment days.

Another is the hiring of a paid administrator, albeit one who for years put in untold volunteer time.

"At first, we were resisting structure," acknowledges Sadowsky, "but eventually found it necessary." A 27-year Woodacre resident, Sadowsky retired from a government job in 1990 only to take on the congregation project just two years later.

Sadowsky wanted to provide her daughter "with some cultural and religious background," and was looking for a way to pursue her own religious practice as well. She, too, had tried other Marin congregations, but couldn't find a fit.

"You know, West Marin is a little bit off the mainstream," she admits. "A combination of distance and a feeling of comfort" propelled her to see if there was any general interest in starting a Jewish congregation in the valley. She first broached the idea with people she knew, then placed a notice in the January-February 1992 issue of "Stone Soup," which generated about half a dozen calls from people she did not know. From that first meeting in her home, the small group assembled a few weeks later for their first Shabbat. Then came Purim, Passover and the ball continued rolling. The group grew by word of mouth, picking up The Lost Tribe from the Point Reyes area, then members of the San Anselmo-based Barah and, more recently, some whose children attended Marin Kindershul, which has dissolved.

In addition to the religious school, the congregation holds twice-a-month Shabbat services, holiday services and festive gatherings, and is becoming more actively involved in doing volunteer work.

The congregation, located at 6350 Sir Francis Drake Blvd., is a registered nonprofit, has a functioning board of directors, and employs a 30-hour-a-week administrator, Laurie Chorna.

The congregation also boasts a Web site (which bears its Hebrew name, Gan HaLev, or Garden of the Heart). The site — www.ganhalev.org — provides general and background information, a calendar of events and details on the religious school and other activities. A narrative characterizes the membership as "post-denominational Jews."

The group is not affiliated with any stream. "We don't feel tied to any particular group of Jewish practice, so we're very inclusive," says Sadowsky, who grew up in a Conservative kosher-keeping home in Brooklyn, N.Y. "We leave a lot of room for people to find their own path and their own way."

Knepler, remembering that first meeting in Sadowsky's living room, gives her a lot of credit. "She revealed right away that the congregation existed in her mind, and the people in the room were to be the congregation. It was calling on all the chutzpah that she had."

He, for one, "was quite happy to join up."

From that point on, the valley's "garden of the heart" just kept growing. Says Knepler: "Michael [Chadwick] and I and a couple of other people just started adding our dreams and our skills."