Ma-ma-ma.
Was that a first word? Hmm? Though your baby is probably still simply parroting sounds, once she starts babbling in distinct syllables, her "conversation" can sound so much like language that it's hard to tell. Consider this her final dress rehearsal for putting those syllables together in a way that has real meaning.
What to say back: Talk about the things around her so she'll connect objects with words. Just don't assume "bo-bo" means "ball" if she says it while reaching for her shoe. "Notice where your child is looking before you label an object. It's very adaptive for babies--and a lot of parents do it naturally," says Jenny Saffran, Ph.D., director of the Infant Learning Lab at the University of Wisconsin-Madison.