Our ratings are generalizations, and they're not a guarantee of how any breed or individual dog will behave. Small, delicate, and potentially snappy dogs such as Chihuahuas aren't always so family-friendly. You may be surprised by who's on that list: Fierce-looking Boxers are considered good with children, as are American Staffordshire Terriers (which are considered Pit Bulls).
Being gentle with children, sturdy enough to handle the heavy-handed pets and hugs they can dish out, and having a blasé attitude toward running, screaming children are all traits that make a kid-friendly dog.