On its 18th birthday in 1979, Temple Beth Torah of Fremont got the best good chai charm that a congregation can ask for — a new rabbi with staying power.

This week, that rabbi, Steven Kaplan, got a chance to celebrate his own 18th anniversary at Beth Torah, while the Reform synagogue marked its double-chai with a celebration.

Why all this preoccupation with the number 18? Because in gematria, Hebrew numerology, 18 is associated with the letters that spell the word "chai." The word itself translates as "life," "luck" or "good fortune," and with so many multiples of 18 floating around Beth Torah, it's easy to see what all the fuss is about.

For their Chai, Double-chai bash, Kaplan, congregants and a handful of temple founders made merry Saturday with cocktails, dinner and klezmer.

For Kaplan, the post was his first senior rabbi position. A Cleveland native, he would in 18 years become a central figure of the Tri-cities and Tri-valley Jewish communities as well as an activist in local and international multicultural affairs.

His synagogue, in its 36 years, has become a decisive force in expanding the local Jewish community from the temple's 13 founding families to the present 300 member families.

"Jews won't move into an area without a fully functioning temple," says Florence Silver, a 35-year member who has kept track of Beth Torah's history. "As our temple improved in services, Jews [then] were willing to move into the community."

Now, several Jewish real estate agents in the area are quick to rope in a browsing family that might otherwise move nearer to the next closest synagogues in San Leandro and San Jose.

Yet Jews living in even farther-flung communities such as San Ramon, Pleasanton and Livermore like Beth Torah so much that they're willing to make the trek, Silver says.

Keeping a good rabbi, she adds, has strengthened Beth Torah's drawing power.

Kaplan has been the synagogue's longest-term rabbi to date. Under his leadership, the synagogue on Paseo Padre Parkway constructed more classrooms, offices, a playground and a social hall. It offers Torah study, youth group activities and last year began to offer additional Hebrew classes in Dublin for Tri-valley children who cannot easily get to Fremont on weekday afternoons.

Whether holding activities at remote locations or visiting congregants, Kaplan jokes that he sometimes feels like a rural doctor making housecalls.

The rabbi for more than a decade spurred his congregants to support the Ethiopian Jewish evacuation and resettlement in Israel. When Kaplan asked board members for permission to accompany fact-finding missions to the African state and Israel, they enthusiastically backed him.

"It is a very loving congregation," Kaplan said. "They were some other Jewish families," Leinkram said.

While Kaplan's first wife, Debby, was dying of breast cancer, congregants took care of the family's shopping and cooking for more than a year, he said.

Kaplan also has gained wider visibility for the area Jewish community by involving them in interfaith work with the Tri-City Ministerial Association, a coalition of churches, mosques, Buddhist temples and other area religious institutions. Once a year, the association hosts annual interfaith Holocaust and Thanksgiving services.

Last Saturday's celebration was particularly sweet for a remaining handful of synagogue founders.

In a recent interview, founder Sara Leinkram reminisced about the early days when 13 families began to meet in schools, clubhouses and a Masonic hall in 1961.

"If we wanted to be with other Jewish families, [a synagogue] was the way."

Fremont in the 1960s was a somewhat disjointed community comprised of five districts, connected by suburbs and sprawling farmland. With no center to the community, it was difficult for Jews to encounter one another.

A couple of founders met while buying holiday greeting cards, Silver recalled. They held services in homes and rented halls for several years until there were enough families to purchase their first synagogue, a four-bedroom home in Fremont's historic Niles District. They received their first full-time rabbi in 1968.

The congregation grew rapidly as more families moved to the area. By 1971, they purchased a lot at the site of their current synagogue, though they did not build the synagogue until just before Beth Torah's 18th birthday, the year that Kaplan was hired.

Leinkram says she cannot separate cherished family memories from Beth Torah. Her daughter was a baby when she and husband Bertram became founders.

In 36 years, she has seen all her children celebrate their b'nai mitzvah and a daughter marry at the synagogue. Her late mother was also a member.

"It's a matter of being integral to the family," Leinkram said. "If my grandchildren lived here, they would participate [at Beth Torah] too."