Thirty years ago, the employees at Rubin Postaer and Associates weren’t worried about developing a social media campaign for a client or figuring out how to build a company’s presence through a smartphone app.

But potential consumers have dispersed to more places than perhaps ever before, pushing the Santa Monica-based firm to adapt constantly to changes in the advertising world.

That knack for anticipating trends is among the reasons why RPA is on the eve of celebrating its 30th anniversary, a milestone that becomes official later this year.

“We’re still helping clients build brands and drive traffic to their retail outlets, but there are now so many more options from a media engagement standpoint,” said Bill Hagelstein, the firm’s CEO and president. “We didn’t have mobile, search and social back then, but our industry has grown. … There are more and more opportunities and more areas to attempt to engage, but it’s an elusive and more difficult customer to engage with these days.”

Hagelstein has seen firsthand how RPA has transformed over the years into one of the most well-known advertising agencies on the Westside.

He was hired in 1977 at what was then the West Coast office of New York-based Needham Harper and Steers. Nearly a decade later, in 1986, the advertising business was jolted by the creation of Omnicom, a merger of Needham Harper with two other big firms in the field.

But companies are reluctant to contract with advertising agencies that also serve their competitors, Hagelstein said, and the merger made several clients uneasy.

With the goal of retaining Honda as a client, Gerry Rubin and Larry Postaer, who were running the L.A. branch of Needham Harper at the time, splintered from the merger and continued operations with the same employees under a new name: Rubin Postaer and Associates. It’s the agency that exists today, and it still has the automotive giant as one of its clients.

Hagelstein, who has been with RPA for much of its history aside from an eight-year stint at another firm, said Santa Monica has played an important role in the success of the agency, which now has about 500 of its 625 or so associates based in town.

Years ago it was housed in other parts of Los Angeles, including Westwood, but executives sought for RPA what Hagelstein called “a more hip and cool environment.” The agency moved to 2nd Street in Downtown Santa Monica, adding office spaces in the Third Street Promenade area for strategic planning and design. On Dec. 1, 2003, RPA settled in its current location at 2525 Colorado Ave.

Hagelstein said the agency was forward-thinking in its creation of an interactive and digital wing in 1994. He added that the firm has been able to adjust to an industry climate in which major clients often hire several different advertising specialists instead of working with one agency.

“We think we’re well-positioned for the future,” he said.

RPA carved out a prominent position in this past year’s Super Bowl, the mecca of television advertising. It worked with Honda on a spot that featured singing sheep, helped on an ad featuring Jeff Goldblum and created a clever piece for a coffee company that won a competition through Intuit.

“We’re not a public company, so we’re not driven by earnings per share, and we focus on clients as people first, driving their business goals,” Hagelstein said. “With the elusive customers that you’re trying to reach, you really have to focus on people first.”

Those people include the employees at RPA, which Hagelstein said has no plans of leaving Santa Monica.

“Being in a creative business, people like being in Santa Monica and what it represents, the culture, the community,” he said. “We like being here.”