My dogs bark for basically two reasons....either someone is at the door or there is a critter in the woods behind our house. The barking at the door doesn't last very long so I usually don't even bother to tell them to stop. The barking at the critters is another thing, especially if it is late at night or early in the morning (neighbors, you know ). I shout "No Bark!" Sometimes it works with Bella but it never works with Ripley.