Hi A.. Did you prepare your girl about the baby coming? I too have a 3 1/2 year old and a 3 month old. It's tough working making the toddler feel secure in her new place. My girl acted out the first month we were home with the baby, hitting, screaming, tantrums, talking back. Bedtimes are still hard because the baby is up when she is supposed to be sleeping. I try to take 'special time' with just her during the day, dad does too. We each take turns letting her pick something to do; read, play games, or cuddle...whatever SHE wants to do. Sometimes she even picks going to get an icecream. It has really helped so far. I also include her on the babies things. She helps to wipe the baby, helps hold his head while I'm nursing, gets diapers-burp cloths-clothes-etc.. I've made sure to take her place as only and youngest child to that of the big sister. She even has a shirt that I found at babies r us that says "I'm the big sister". We also enrolled her in preschool with kids her own age. Just to get her out and let her be her own person. I wish you the best of luck, please let us know what you find that helps you.