Well, just like any other breed of dog, they can be made to be aggressive. (I'm not saying this of Ian's dog) As a breed, they are definately mild in temperament. They also have sort of a "mean" look, and often are confused with "pit bulls", a breed that has a poor reputation. Of course, they are pretty good about protection, especially with children! Once, when our youngest girl was ten, we took her and our boxer for a ride downtown. She and the dog was sitting in the back seat with the top down while we went inside to take back a video. When we came back, we could see that a man was trying to talk to our girl, and the boxer was facing him with teeth bared! This was not a normal thing for him as he usually liked to be petted by strangers. The dog must have known something we didn't!