At one venerable San Francisco social club, the I’s have it.

This year marks the 50th anniversary of the Irish-Israeli-Italian Society, and members are going all out to celebrate. The society’s annual St. Patrick’s Day luncheon this week drew more than 250 to the San Francisco Italian Athletic Club.

The Triple I — as it was referred to in a San Francisco Chronicle society column a few years ago — is a holdover from the days of old-fashioned civic bonhomie, when politicians, policemen and business leaders rubbed shoulders (and bent elbows together after proclaiming, “Next round’s on me.”)

This club brings together the Irish, Jewish and Italian communities, all of which did much to make San Francisco the prosperous melting pot it is today.

Quentin Kopp, the former state senator, San Francisco supervisor and San Mateo County Superior Court judge, attended his first Triple I function 47 years ago and is current co-president representing Team Jewish. At 86, he has a long memory for city politics and says the Triple I represents San Francisco at its best.

“The purpose,” Kopp said, “was to rouse and reinforce the spirit of cooperation between three then-major ethnic groups in San Francisco.”

The schedule for the March 11 luncheon included a benediction from Rabbi Moshe Levin of San Francisco Congregation Ner Tamid and remarks from the locally based consuls general of Ireland, Italy and Israel. Kopp introduced the many dignitaries present, key state legislators among them. After that came the handing out of good citizenship awards, a reedy serenade from a bagpipe band and finally, a corned beef and cabbage feast.

Last October, the society had a luncheon to celebrate Columbus Day. And at last year’s St. Patrick’s Day luncheon, Harvey Rose, a longtime accountant and budget analyst, and a member of the society’s advisory committee, was the distinguished honoree.

Eating and shmoozing are what the Triple I has been about for the past half century. It was founded by the late San Francisco lawyer Nate Cohn and George Reilly, a legendary Irish American raconteur who served on the board of supervisors in the 1940s and twice ran for mayor.

“They got together and formed the Irish-Israeli Society,” Kopp recounted. “It was dedicated to the proposition of a lunch to celebrate St. Patrick’s Day and another to celebrate Israel Independence Day.”

A year in, “Italian” was added to the club name, thanks to the urging of a garrulous police captain named Charlie Barca, who then became a Triple I co-president. The first and only Triple I secretary was — and is — John Shimmon, now in his 90s.

Shimmon is of Lebanese extraction, which is OK by club rules. Anyone of any ancestry is welcome to join, and there is no membership fee. There is no website, either, so for more information, contact [email protected].

To make it another 50 years, Triple I leaders know they must attract younger members. Adriene Roche, 49, is the society’s new Irish co-president, replacing former San Francisco treasurer Mary Callanan, who succeeded Reilly.

Roche, a native San Franciscan whose ancestors came from Galway, Ireland several generations ago, has attended Triple I events for 10 years. She enjoys the luncheons and the guest speakers, who are usually experts on history or current events.

But she has more reasons for admiring the Triple I.

“It’s a uniquely San Francisco organization,” she noted. “You meet people you’ve read about over the years, iconic San Francisco natives, people who have made a difference in the city. You see people showing up for lunch with a tie and jacket on, enjoying each other’s company.”

San Francisco has been a haven for Jews ever since the Gold Rush days, which explains the exceptionally high-impact role Jews have played in the growth of the city. Kopp says this is more important than ever, as anti-Semitism appears to be on the rise around the world

He says the Triple I engenders crucial support for Jews and Israel.

“You have the presence of a strong rabbi [Levin], a capable Israeli consul general [Andy David] and the historic American theme of nationalities that have achieved success,” Kopp said.

As proof, Kopp points to the many friendships that have grown out of Triple I membership.

“You can observe it at the tables,” he said. “People want a congregation of friends.”