I would say "no hitting" very firmly and take your 2 year olds hand off the baby. Show the 2 year old how it hurt the baby (like "look, you made the baby cry, Owie!) Then say again very firmly "no hitting". It will take consistency and if your 2 year old doesn't get it, you will have to start time-outs. A 2 year old is not too young to understand consequences for bad behavior. Just 1 or 2 minutes should be okay. It is a natural consequence. Sometimes I add "when you want to be nice to the baby, you can come back out and show "nice" which is taking your 2 year old by the hand and gently stroking the babies arm to show your toddler how to be nice. It is also a very early way to apologize, toddler-style.
at 11:06 PM on Oct. 27, 2008