My daughter was almost three when we got our puppy Maggie last year. There have been times when we have had to keep them separated by baby gates much of the time. Until Maggie was seven or eight months old I had to keep her on a leash at all times (and attached to me) in the house so I could control. They would also have to "take turns" running in the yard- puppy went on leash when kiddo wanted to run. During the rough phase (3-7ish months) my daughter was often frustrated because she could not play with Maggie as much she wanted to. During that biting/jumping/clothing grabbing phase I let my daughter play with Maggie in very controlled ways, some examples: I held the dog and my daughter hid small treats around the house/yard, I bought a doggie puzzle and my daughter filled it with the treats and set it down, my daughter kicked a soccer ball and hit tennis balls with her racket for Maggie to chase. We also went to Build a Bear and let her build her own puppy, she is really into pretend play, so when I would brush Maggie, she brushed her "puppy", she could walk the puppy around the house, feed it, train it, etc. Now with Maggie at a year old things are getting much easier. There is an awesome friendship between the two now. I still would never leave them alone unsupervised, but they spend most of the day together now mostly problem free. It will get better!!!!