Think about it:
Before the baby entered your family, your toddler was told he'd have a wonderful little brother to play with, and how much fun it would be. Then the little brother is born and your toddler is thinking, "Are you kidding me? This squirming, crying, red-faced lump that takes up all your time and attention is supposed to be FUN?" He then "plays" with the baby in the only ways he knows how. He plays catch. You yell at him for throwing toys at the baby. He plays hide-and-seek. You screech that he's trying to suffocate the baby with the blanket. He gives the kid a hug, and you explode in fury. Is it any wonder that your toddler is confused?

Teach:
Your first goal is to protect the baby. Your second, to teach your older child how to interact with his new sibling in proper ways. You can teach your toddler how to play with the baby in the same way you teach him anything else. Talk to him, demonstrate, guide and encourage. Until you feel confident that you've achieved your second goal, however, do not leave the children alone together. Yes, I know. It isn't convenient. But it is necessary, maybe even critical.

Hover:
Whenever the children are together, "hover" close by. If you see your child about to get rough, pick up the baby and distract the older sibling with a song, a toy, an activity or a snack. This action protects the baby while helping you avoid a constant string of "Nos," which may actually encourage the aggressive behavior.

Teach soft touches:
Teach the older sibling how to give the baby a back rub. Tell how this kind of touching calms the baby, and praise the older child for a job well done. This lesson teaches the child how to be physical with the baby in a positive way.

Act quickly:
Every time you see your child hit, act quickly. Firmly announce, "No hitting, time out." Place the child in a time-out chair or room with the statement, "You can come out when you can keep your hands to yourself."

Praise:
Whenever you see the older child touching the baby gently, make a positive comment. Make a big fuss about the important "older brother." Hug and kiss your older child and tell him how proud you are.

Watch your words:
Don't blame everything on the baby. "We can't go to the park; the baby's sleeping." "Be quiet, you'll wake the baby." "After I change the baby I'll help you." At this point, your child would just as soon sell the baby. Instead, use alternate excuses. "My hands are busy now." "We'll go after lunch." "I'll help you in three minutes."

Give extra love:
Increase your little demonstrations of love for your child. Say extra I love yous, increase your daily dose of hugs, find time to read a book or play a game. Temporary regressions or behavior problems are normal, and can be eased with an extra dose of time and attention.

Get 'em involved:
Teach the older sibling how to be helpful with the baby or how to entertain the baby. Let the older sibling open the baby gifts and use the camera to take pictures of the baby. Teach him how to put the baby's socks on. Let him sprinkle the powder. Praise and encourage whenever possible.

Make each feel special:
Avoid comparing siblings, even about seemingly innocent topics such as birth weight, when each first crawled or walked, or who had more hair! Children can interpret these comments as criticisms.