Thinking of adopting a shelter dog, but have heard some horror stories about pups turning into psychotic, untrainable balls of fur? There's a trick to picking the right one. 

The key is friendliness. That’s the No. 1 quality to look for, says canine behavior expert Sue Sternberg, author of Successful Dog Adoption.

How to spot it? Look for a dog that:

  • Comes to the front of his kennel, eager to make a connection.
  • Keeps his ears back (not forward and aroused) and his forehead smooth (not wrinkled in anger).
  • Wags his tail wide and low—a sign of friendliness, says Sternberg—not high above his back.
  • "From the front, especially when he’s looking at you, the sociable dog’s head and spine won’t be in full alignment,” she says. “That’s more military, like someone ready to go to war, not meet a friend.”

Of course, a dog needs to not just look friendly but also be friendly, so:

  • “Take him into a room on a leash, lean against a wall, and ignore him for 30 seconds. Then sit and keep ignoring him while you watch his behavior for 10 seconds.” Meaning: Resist the urge to be affectionate until the time has passed. "You want a dog that wants your attention, petting, and loving, even if it’s jumping up on you—jumping up, as long as it’s gentle, is a training, not a temperament, issue,” Sternberg says. “But you don’t want the one that yanks on his leash trying to get away from you.”
  • Pet the dog using slow, deep strokes. “The easiest dogs will become calm and relaxed with stroking; difficult dogs will get more stimulated.”
  • Next, if the shelter allows it, unleash the dog and walk around the room to see if he stays close and attentive.
  • Finally, ask if you can take him out for a leash walk, and try to get within about 10 feet of another dog (no closer). Keep him moving and ask him to pass. You want a dog that doesn’t pull or strain to fight, and refocuses on you easily after you pass.

A last note: Always pick a no-kill shelter—we like New York’s North Shore Animal League, the San Francisco SPCA, and the nationwide Best Friends Animal Sanctuary.