Robots with human-like personalities, both friendly and hostile, have long been familiar to science-fiction fans. The popularity of robots soared to new heights with the Star Wars movies as R2-D2 and C-3PO charmed moviegoers worldwide. But even the android C-3PO communicated its timidity through body language and vocal intonation, not facial expressions. Now, researchers are poised to put a human face on C-3PO and chums. And while it will be decades before we know robots as smart as Lieutenant Commander Data, the humanoid from Star Trek: The Next Generation, expressive robot faces will show up a lot sooner--perhaps by next Christmas, on toys. Robots' facial expressions are more than just the stuff of toys, though. In order to maintain natural give-and-take communications with people, robots should be able to produce their own facial clues, "like a look of confusion when you say something the robot doesn't understand," says Cynthia L. Breazeal, a reseacher at Massachusetts Institute of Technology's Artificial Intelligence Laboratory. To do that, robots will also need to comprehend the silent language of human facial expressions, she says. Combine the work on artificial faces with other research--such as the progress in robot locomotion, including walking on two legs--and robots could become as familiar in real life as they are in science fiction. Here are some scenes from labs around the world, collected for Robo Sapiens, a book by Peter Menzel and Faith D'Alusio to be published by MIT Press next fall.