The San Francisco Mime Troupe has a storied history that dates back to its founding in 1959, yet, many people still believe that the group is made up of mimes.

The group has nothing to do with those white-faced characters who perform in parks, pantomiming about being locked in invisible phone booths. The San Francisco Mime Troupe produces what it calls "socially relevant theater of the highest professional quality," bringing it to the broadest possible audience. The plays are musical political satires and make a lot of noise.

The company is like most theater companies with a support staff and core group of artists. It often goes outside the group for other artists, depending on the particular production, and those artists can become part of the company over time.

This year's show, "Posibilidad, or Death of the Worker," has four regional performances next week in Nevada City, Davis and Sacramento. In the finest Mime Troupe tradition, "Posibilidad" is an agitprop melodrama focusing on the downsizing of American workers.

The Northern California performances are a homecoming of sorts for one of the lead actors, Brian M. Rivera, who started his theater career at Sacramento's Jesuit High School.

Rivera plays two roles in the show and sings several songs along the way. First, he's Manny, an optimistic but dorky worker, one of the few left in the American factory where most of the play takes place. Manny's in love with Sophia, a new worker from Argentina. Rivera also plays Manny's opposite, Indelecio, Sophia's lover from Argentina, who's a brash Marxist revolutionary.

Rivera got hooked on theater after seeing a Jesuit High production of "Into the Woods."

"I was completely amazed by their production and so I started trying out for the shows," Rivera said by telephone from the Mime Troupe's San Francisco office.

Because he was in a carpool from his parents' Greenhaven home (where they still live), Rivera couldn't take the school's evening drama classes. But he was in the Men's Choir, which helped him finally land a role in his senior year in "Guys and Dolls."

Rivera then moved on to Sacramento City College, where he said he stayed "far too long," getting caught up in the theater milieu on campus. He did numerous shows, with special emphasis on the summer Shakespeare in the Park program, where he played Benedick in "Much Ado About Nothing," Roderigo in "Othello" and Macbeth, among others.

Though his Filipino parents weren't initially overjoyed with his career path, Rivera said they now even suggest he could move to the Philippines to work.

"It took me a long time to declare my major, but after that I started pursuing it single-mindedly," Rivera said. He transferred to San Francisco State, studying theater and making friendships, which resulted in his first job with the Mime Troupe five years ago in "Doing Good."

"I don't want to say I've been lucky, but I've had enough great opportunities that I've been able to keep going."

Rivera has worked at some of the Bay Area's major theaters, including Berkeley Rep, Campo Santo, Word for Word and the Shotgun Players.

"I think Denzel Washington said, 'If you can think of anything else besides acting you'd rather do, then go do that.' I can only think of this, so here I am," Rivera said.

Rivera was cast in the current show before writer Michael Gene Sullivan had even written it. Sullivan said that is par for the course when working with the Mime Troupe.

"Where we start is with the burning issue. We don't have an artistic director, we have a collective," Sullivan said. He joined the Troupe in 1988; in 1992 he became a contributing writer, and was named resident playwright in 2000.

The collective starts meeting late in the year, talking about issues it thinks will be big in eight months.

"We have to predict the future, which is always fun," Sullivan said.

"What's the thing people are going to have the most questions about, the most misinformation about, the most emotion about, that they're going to need to deal with?"

Eventually, they come up with what they want to tell. The writing committee then hashes out storylines for the show. Once the collective OKs it, the writer or writers take over and write as much of the show before rehearsal starts. Also, because it's a musical, a composer gets involved.

"He brings in a song, and people make comments about that, just like they did with the script. Then you have to rewrite the scene so the song makes sense."

Though the process sounds lengthy and rather communal, Sullivan said it's almost like a big commercial theater production.

"It's very similar to the process you would go through if you were creating a big Broadway musical. Only we do it in five months instead of four years," he said.

And then there's the political part, which isn't necessarily mainstream, but has its own following.

"The people who know what we're about are very politicized and opinionated," Rivera said.

"A lot of them have been coming for decades to see Mime Troupe shows. Not just in San Francisco but everywhere."