10 month old puppy growls and nipps at people

Question
I thought I was doing a good job socializing my Chow/ pit or boxer mix puppy. I got her at 4 months old, I started taking her to the dog park almost every day about 6 months old. She was doing great playing with the dogs never showed any aggression toward people. She goes on hikes and walks where she sees people and doesn't bark as we walk past.  At about 8 months she started baking at people at the dog park and tried to nip the vet. She is a very sweet and loving dog she doesn't go after people it is when they come up to her and want to pet her. I could stand with her on a leash and have a conversation with a stranger and she won't do anything. As soon as the person directs their attention to her she will start growling and if they try to pet her she try's to nip them. How do I brake her of this?

Answer
Socializing means more than just taking a puppy out in public. It means letting strangers pet and hold that puppy and give it good things to eat, and it may be too late for you to remedy this now after ten months.

First, get her into on-going obedience classes for several months and work with her every single day. Start practing "Nothing in Life is Free" with her. http://k9deb.com/nilif.htm

Have some really good treats that she likes (chicken, cheese, etc.) handy and give it to people for them to feed her. No petting allowed until she is comfortable with taking and eating food from strangers.

You might have to get an animal behaviorist to help you with this one. You should be able to get the name of a good one from your veterinarian.