Long a haven for literary outlaws, the Peninsula’s cognoscenti and readers just interested in a good browse, Kepler’s Books and Magazines celebrates its 50th anniversary on Saturday .

Founder Roy Kepler opened the bookstore on May 14, 1955, and four locations later, the store continues to flourish as part of Menlo Park’s cultural scene .

“He was looking for an opportunity for him to have a livelihood that didn’t require him to compromise everything in working for somebody else,” said Clark Kepler of his father, who was a lifelong activist.

“His passion in life was social activism and nonviolence. In the ’50s, he was working for different causes, he was a founding staff member at KPFA radio, he was involved in doing a lot of things that weren’t career-oriented and didn’t pay much,” Kepler said. “When he married and started to have a family, I think he recognized that he needed a career to sustain a family.”

The senior Kepler had done some research on the publishing business and found that bookselling matched his interest in the exchange and flow of ideas. Roy Kepler opened his bookstore with only a few thousand dollars, but it soon blossomed into a cultural epicenter and attracted loyal customers from the students and faculty of Stanford University and from other members of the surrounding communities who were interested in serious books and ideas.

“There was a perfect storm of occurrences that happened right when Kepler’s opened,” Clark Kepler said, not least of which being what he terms the “paperback revolution.”

The notion of selling texts in inexpensive paperbound volumes was a revolutionary notion in the publishing trade, making Kepler’s one of the vanguard of booksellers on the West Coast doing the same, including spiritual siblings City Lights Books in San Francisco and Cody’s Books in Berkeley.

“After the Second World War, trade paperback books suddenly became available. There was a reaction from the book industry — traditional booksellers didn’t view paperbacks as real books,” Clark Kepler said. “It was a time when literature was available in paperback very inexpensively and publishers were making classics available that heretofore you could only find in a library, if at all.

“(Roy Kepler’s) objective was to have a bookstore that offered a full range of ideas and information so people could decide for themselves what they wanted to read and want they wanted to believe,” Clark Kepler said. (This philosophy is pithily preserved on T-shirts commemorating the store’s 50th anniversary with a quote from Kepler describing the store’s stock: “You’ll find the views of communists, socialists, conservatives, know nothings, humanists, pacifists, libertarians, semanticists, scientists, etc.”).

“He always had his own beliefs and they were present in what Kepler’s did and presented. The people that he employed, especially in the ’60s, were a lot of Stanford students, draft resisters, people in ‘the cause’ — the bookstore took that on very rapidly.”

Kepler describes the original location (opened in 1955 next to the Guild Theatre) as a “hole in the wall” at under 1,000 square feet. The bookstore’s legend took root, however, at its 825 El Camino Real address, where it began to grow exponentially in the hothouse of the 1960s.

In fact, in 1962 Roy Kepler opened a second store in south Palo Alto. Two years later, it moved to the Village Court Shopping Center is Los Altos. (The store was sold in 1981, changed names and went out of business a few years later.)

By the 1980s, the main store had moved to a Victoria Drive development (off El Camino) and expanded to about 5,200 square feet, until transplanting to its current 10,000-square-foot location, back on El Camino Real, replete with large windows and a layout that suggests something of a garden of literary delights.

Clark Kepler vividly remembers being a child surrounded by the posters lining the walls and ceiling of the store and the fact that customers often smoked indoors and put their cigarettes out on the concrete floor.

“It was very reflective of what was going on in the counterculture,” he said.

Though the bookstore found immediate fans and steady patronage, it also received some backlash from more conservative elements of the community.

“As much as there were a lot of supporters, there were some people who didn’t like what was going on there,” Clark Kepler recalls.

“When I came to work at the bookstore in ’79 as a young man, I talked with customers that were middle-aged at that point, and I got these reflective stories of what it was like for them, what Kepler’s meant to them in their formative years and how important it was.”

It was apparently important enough to disobey parents and other authority figures who forbade their children from going to the store.

“There was a theme that emerged from each one that sort of went like, ‘When I was kid my mom told me never to go to Kepler’s, it was forbidden.’ Or, ‘My rabbi told me never to go to Kepler’s’ or ‘My principal told me never to go to Kepler’s.’ They had these authority figures telling them to stay away from Kepler’s and the punch line to every story was ‘So I came.’ ”

Clark Kepler, now in his late 40s, grew up in the store and learned the business from the bottom up — he began in the receiving department at age 21 after studying environmental ethics in college. “I had that passion of youth to save the world and that sort of thing,” he said, with a laugh.

He had little idea at the time, however, that he would later take over the store. It wasn’t until his father was diagnosed with Parkinson’s disease that the younger Kepler was faced with the possibility of running the family business. He was initially reluctant, and his father briefly entertained an offer to sell Kepler’s.

“It was one of those moments — sitting around with my mom and dad, the CPA and the lawyer having this discussion. As Dad was describing how he needs to do this, I was thinking ‘Here I am trying to save the world and I have this opportunity to do something real here,’ ” Clark Kepler said.

“It’s been 26 years since then. I care deeply about books and enjoy reading. My passion is about bookselling and knowing what a good independent bookstore can do for a community and the importance of the written word.”

Clark Kepler’s commitment and accomplishment in the trade eventually garnered him recognition as Bookseller of the Year by Publishers Weekly. Kepler’s success can be attributed, in part, to his ability to remain versatile and dynamic in the face of a rapidly changing media landscape where he faces competition not only from online point-and-click bookselling but the new way in which the written word is distributed.

“Independent bookselling is very different than it was in the ’50s, ’60s, ’70s, ’80s and ’90s. It changes every year almost,” Clark Kepler said. “Our job is to remain vibrant and relevant. What I’ve endeavored to do is maintain the best of the Kepler’s history and tradition in terms of our connectedness to the community and our service and, at the same time, not lose sight of the fact that we’re in a business and need to be profitable.”

Kepler also continues the tradition of live author readings with a series that spans the gamut from fiction writers to politicos and even the occasional movie star.

“We hosted Jane Fonda a couple weeks ago and Lauren Bacall the month before. It seemed like we had a celebrity season,” he said. “We don’t say that we’re trying to do an ‘actresses month’ or anything like that, but it does evolve in a certain way, it seems. Right before the elections, we had a whole political season where we had Al Franken, Molly Ivins and Barbara Bush.”

The bookstore also remains vigilant about bringing new voices to the fore — authors who often reach their first audiences through independent bookstores only to be appropriated later by the larger chain stores.

“What we endeavor to do is bring in established writers and those who are pre-eminent in their time, as well as up-and-coming writers — new voices that we believe have written something relevant and may be at the beginning of a literary career,” Kepler said.

“That’s one of the strengths that independent booksellers have and one of the things that the publishing world values — we have our fingers on the pulse of what America is reading. We break out new books that become literary phenomena. Independents will often be selling them before the chains are aware of them. Once they get established, the chains are all over them and have them in spades.”

In the meantime, Clark Kepler and the bookstore that bears his family name will continue to fight the good fight.

“As challenging as the industry and the economy is, the value of what we do is intrinsic. I feel honored to be in a career that has that much meaning to me,” he said.

Kepler’s Books and Magazines celebrates its 50th Anniversary 1-4 p.m. Saturday, 1010 El Camino Real, Menlo Park. Live music, performances, games and prizes. All items are 20 percent off all day. (650) 324-4321; www.keplers.com.