It is hard to overstate the benefits of using sign language.  This tool is perfectly aligned with responsive parenting.  Most babies naturally develop gestures that indicate their preferences before they are able to say words, and using American Sign Language (ASL) simply allows babies more opportunities for self-expression.  In my family, signing allowed us to largely skip over the era of inexplicable tantrums and meltdowns that precedes verbal language development for many, if not most, hearing babies.  (This is not to say that we have not had our share of tantrums! It's just that in the pre-verbal stage they usually had nothing to do with not being able to figure out what my older daughter was expressing.)

Even as late as 22 months, when our older daughter’s speech was still developing, she would reach back into her toolbox and sign a word when mama’s powers of translation were faltering. My younger daughter, who is approaching 10 months as I write this, has just begun waving "bye bye," the hallmark of being ready for signing. So we're eagerly anticipating the fun and usefulness all over again!

For general information about the theory and practice of baby sign language:

• Sign With Your Baby by Joseph Garcia.  This kit comes with a book, laminated list of signs, and a DVD.  It is helpful for parents of babies who wish to start sign language but aren’t yet comfortable with their babies or toddlers watching TV.  Garcia uses ASL signs or modified ASL signs for younger babies.  Most advocates of using ASL with babies prefer it to invented signs (“baby signs”) because it is an actual language.

• Baby Signs by Linda Acredolo contains the same core emphasis on the benefits of signing with your baby, but promotes the use of invented signs.  Acredolo’s view is that some ASL signs are simply too complex for babies to imitate. 

Two incredible ways to directly encourage baby sign language (these make wonderful gifts for new parents):

• Baby Signs board books by Linda Acredolo include Baby Signs for Mealtime, Baby Signs for Bedtime, and My First Baby Signs.   I began teaching my older daughter signs for “nurse,” “more” and “potty” around 7 months, it was not until close to 12 months that she began to sign back to us.  The reason for our breakthrough?  Baby Signs board books sent as a gift from a close friend.  My daughter loved looking at the pictures of babies making the signs, and she began to imitate them.  And then it was a communication explosion!
  
  
• Signing Time is a whimsical and highly effective series of DVDs, CDs and books by Rachel de Azevedo Coleman and Emilie de Azevedo Brown.  This is an extremely high-quality product.  Per the recommendation of the American Academy of Pediatrics, I was planning on limiting access to TV for the first two years until I watched some Signing Time clips online.  I guessed immediately that my older daughter (who had shown little interest in Sesame Street at that time) would love them and learn from them, and I was right.  (As a side note, my current understanding is that the AAP’s recommendation is meant mostly to deter parents from substituting TV time for human face time, or for allowing children to watch several hours of TV each day.  Neither is a concern in our case.)  Her vocabulary went from 15 to over 80 signs in two months with Volumes 2, 3, 4 and 7.  Signing Time DVDs are inclusive of kids with various physical challenges and all races, and do not reinforce gender stereotypes (actually, the opposite – one song called “Proud to Be Me” teaches the sign for “boy” and “girl” with parallel images of kids playing sports and other activities!).    Rachel and Emilie have written spectacular original music, which we also purchased on CD to reinforce the songs (several of which were on my daughter’s “must-sing-incessantly” list at one time or another).