"10 Reasons to Let Your Dog Play with Other Dogs:"

1. According to Dr Michael Fox, puppies that play more grow up to be "more intelligent and highly evolved."
2. Dogs who don't play with other dogs as puppies can grow up to be fearful or aggressive toward other dogs.
3. Play teaches inventiveness and problem solving.
4. Play deflects natural aggression and teaches cooperative behavior.
5. Puppies learn how to inhibit their bite when playing with other pups and that's good news for us.
6. It's a REALLY easy way for you to exercise your dog. Your dog will be tired and a wonderful sleeping angel in the house.
7. Dogs are naturally social creatures who crave the attention of humans AND the companionship of other canines.
8. Play is a lifelong activity for dogs, especially when fostered early. Adults solves to play and we have exaggerated this behavior even more in our pet dogs.
9. Dog runs and the parks are a wonderful way for us humans to meet each other and talk dog.
10.  Watching dogs play is just so fun.

(taken from http://www.canisphoto.com/training.htm)