My dog dashes out the door--What should I do?

 Keep identification on the dog at all times.  You have several options.  Teach sit, stay, and a good recall.  Reinforce Fido for staying on his side of the door (“Find it!)  Tether Fido until you can teach him to be more reliable.  Train an incompatible behavior, such as lying down on a mat, instead. 

Figure out what is motivating Fido to dash out the door and provide it for him at home if you can.  He may be looking to play with the children or dogs down the street.  If he is an intact male looking for a mate, have him neutered.  He will be easier to retrain once his hormone-levels have settled down (ask your veterinarian how long this will take).

I teach my dogs to stay by rewarding the dog for staying behind when I open the door or gate. This can be as easy as tossing some yummy treats on the floor as I go in and out of the door or gate.For committed door-dashers, I will put the dog on a leash or tether until he gets the idea that staying behind can be more rewarding than dashing out.