I am a new dog owner, and have found a great rescue puupy, but he has been growling at strangers randomly when my husband and I are on walks.
He is only 4 and a half months old and was delivered by the people at the rescue, but acts like an adult attack dog when certain people approach him. Most of the time he is a regular puppy-very friendly, and lots of kisses etc. but when someone new approaches when I am on a walk alone with him he gets very reactionary. When he is immersed in a situation, he appears to be fine... his tail wags etc, but on walks alone he gets very protective. He is half lab, half cocker spaniel, and will roll over on his back in a second once he is confident... but he has these moments of aggression that I just don't know how to respond to. Can anyone help me?

The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/

As top dog, it is your responciblity to defend the pack from dangerous strangers. Smile and give them a friendly ''Hi!''. If you are relaxed and happy, he should be to. You can even arrainge for ''strangers'' to be carying treats for him.