Boston — Sixteen years ago the characters from the Charles M. Schulz comic strip ''Peanuts'' jumped out of their cartoon squares and onto the stage.
It happened in the fetching Off Broadway musical hit ''You're a Good Man, Charlie Brown.'' In the show's most rousing number, Snoopy made a bowl of dog food seem as appetizing as Beef Wellington as he yelped and pranced out the number ''Suppertime.''
This season Snoopy is back - this time in his own show - and with the rest of the ''Peanuts'' characters looking hardly the worse for wear. The Broadway-bound musical ''Snoopy!!!'' (at the Charles Playhouse here) snips its yuks and its pathos right out of past episodes of the comic strip.
The actors particularly deserve a hearty wag for taking a slightly meandering entertainment and filling it with animation and feeling. Music by Larry Grossman and lyrics by Hal Hackady are engaging, and the songs in general are communicative and tuneful.
Breathing theatrical life into cartoon characters - even if they're characters with an almost tangible personality on newsprint - is difficult. I recently chatted with director Arthur Whitelaw and producer Gene Persson - as well as Snoopy himself (David Garrison).
By now, Mr. Whitelaw and Mr. Persson should be very familiar with Snoopy & friends. They were also responsible as co-producers for pulling together the first Peanuts derivative, a still successful show that even last year was seen in 1,800 productions throughout the world. As such, there are inevitable comparisons between the two plays.
''The biggest challenge,'' admitted Mr. Whitelaw, who co-wrote the book for ''Snoopy!!!,'' ''has been to do a show that would at least equal what we had done before. The other challenge was adding some characters we didn't have in the first show.'' He cites Woodstock (Cathy Cahn), a bird friend of Snoopy's, who can't talk but flutters around the stage communicating a sort of desperate desire to be a part of his life.
Another aim has been keeping it simple. Persson remarked, ''We're a small show. We don't intend to compete with the big musicals. But it's every bit as difficult to do a small musical, perhaps more so.''
Whitelaw explained that ''the cast isn't hiding behind a story, a singing and dancing chorus, or a 36-piece orchestra. They're depending on their own talent.''
The set and costumes (both by David Graden) are also simple - almost to the point of being Spartan. The result is that the characters and the audience are unleashed, for better or worse, to do the work themselves.
''I think that audiences like to work a little bit when they go to the theater,'' Whitelaw said. ''When we first made Charlie Brown it was a very conscious decision not to copy the (cartoon) strip, but to let the audience come to see what we wanted them to see. If a block was supposed to be a television set, what they saw was a television set. We've done the same thing here.''
Much credit belongs to David Garrison, whose performance as the gregarious and fantasy-bound Snoopy is strong enough to survive the times when the play involves the activities of the other characters.
''I don't try to do an impersonation,'' he explained. ''One would only get into trouble. I try to come up with the essence of the character. Snoopy transcends dogdom. Although there's a part of him that says, 'What fools these mortals be,' he would somewhat like to be like them.
''In a way, Snoopy is a bit like so many of us. He's a Walter Mitty with paws. He deals with life's challenges by being a total fantasizer.''
Throughout all this, Charles Schulz, the father of the Peanuts characters, hasn't let these productions run entirely free. Whitelaw and Persson say they've made numerous changes he has asked for.
''Ninety percent of the show is Schulz,'' Whitelaw said. ''The ideas for the songs all came from scripts. In particular, they were the favorites of Gene's and mine.''
''Snoopy!!!,'' in fact, has been around since late 1975, when it opened at the Little Fox in San Francisco for a lengthy run. But before it left, the show became involved in ''legal entanglements,'' in Whitelaw's words.
These have now been removed, clearing the way for ''Snoopy!!!'' to go to New York, where Whitelaw and Persson expect to open before Christmas. Persson said that with the close of ''Annie'' on Jan. 2, ''We'll be the only family show. Hopefully we're going to be the top dog in town.''