The "down" command instructs your puppy to lie down on the floor. This is frequently confused with the "off" command, which instructs your puppy to put all four feet on the ground immediately, and is used to control unwanted jumping. "Down" and "off" are completely different behaviors, taught in different ways and used for different purposes.
Being able to down your puppy is something like being able to park your car: it stops movement. A puppy lying down is less likely to get into mischief. Since pups lie down many times a day on their own, the behavior itself is not the mystery – the trick comes in figuring out how to get the pup to do it quickly and willingly at your command.
This command can be easily taught to most puppies, although they should know the sit command first.
The down command is usually taught either with food rewards or with placement exercises. Note, although food rewards are useful in training, praise and positive voice inflections are preferred. Once your puppy is familiar with the command the food rewards should be decreased, but you should continue to praise your puppy for his correct behavior.
Teaching the down command with food rewards
Start with your puppy sitting next to you. Hold a treat between your fingers and put your fingers in front of your puppy's nose. Rest your other hand on his shoulder blades. Slowly lower the treat straight down, from your puppy's nose to between his paws, and then slowly pull the treat along the floor away from your puppy. This movement should look like a capital "L". Done properly, your puppy's nose should follow the treat and, as it does, he should move into the down position. Be patient and keep trying, he'll get it. Once he's down praise him and give him a treat.
When your puppy is reliably following the treat into the down position, start saying the word "down" as he is moving so that he links the word with the appropriate action. If your puppy stands up when you lower the food it may be that you are not fully completing the "L" movement, or that you are moving the treat too slowly. As well, if you pull the food away too fast or at an angle, your pup may stand up.
What do you do if your puppy refuses to down? Some pups are just not that motivated by the food offered so try a more tempting treat or a favorite toy instead. If you can't get the whole behavior you want, reward your puppy for even the small steps he makes in the down direction. If your pup will lower his head, reward that. Soon he'll lower his head happily, so ask for it lower still and reward his best effort. Slowly, reward by reward, move toward the behavior you want—your pup lying down. Sometimes, training in small steps is the fastest way to reach your goal.
Teaching the down command with placement exercises
There are many ways to place a puppy into the down position—this is one method that is easy and safe. Begin on a rug or other soft surface. With your puppy sitting on your right, reach over and place your right hand on his right shoulder blade. With your left hand, lift up your puppy's left front leg while, at the same time, pressing gently to the left with your right hand. Gently ease your puppy into the down position, then praise him, pet him and give him a treat. Make this a special moment between you and your puppy. Once you get the hang of this technique, it's difficult for your pup to resist this smooth motion.
Success with the down command is not difficult. Just practice it a few times a day, a few downs at a time, and sooner than you might think your puppy will be happily downing for you with a big grin and a waving tail.