How to Stop Unwanted Barking

Found a great article on Dogster. Here is a summary/shortened version that I thought you might find helpful.

Dogs bark to communicate with you. Learning why they bark is the key to stop your dog from barking. Depending on the reason for barking and your own training skill level, you may need to consult with a qualified trainer/behaviorist to assist you with the training. For more on selecting a behavior professional, check out the American Veterinary Society of Animal Behavior guidelines for choosing a trainer.

Just as there are many reasons humans speak, dog barking occurs for a number of reasons. Here are a few of the most common:

Distance decreasing: Distance decreasing barking can also be considered attention-seeking barking. The dog is barking to communicate with the owner - "pay attention to me!"
Boredom: Evaluate your dog's lifestyle. How much physical exercise is she getting? How much social stimulation through appropriate play with other dogs? How much play does she get with you? Is she getting adequate mental stimulation in the form of both training and problem solving? If your dog is barking because of boredom, consider more physical exercise, more positive training, and introduce new toys and games for environmental enrichment (At Cause to Paws we have lots of interactive toys that can help)
Frustration: While some frustration barking is boredom barking, not all boredom barking is frustration barking. Often in class, dogs bark when their owners have poor timing or because the rate of reinforcement is too low, the dog is frustrated because the signals are unclear.
Separation distress (limited vocalization, no injury to self or property), consider how long the dog is left alone - if it is more than eight hours for an adult (even shorter periods of separation are recommended for puppies), find a dog walker or pet sitter to break the day up. Provide her with mental stimulation through puzzle toys, kibble hunts, etc., when she is alone. (At Cause to Paws we carry things like DAP - Dog Appeasing Pheromone - sprays or collars, Rescue Remedy drops, Happy Traveler tablets from Ark Naturals which often helps calm the dog while you are gone or Lavendar Foam can help your dog to relax.Greetings, and exits should be low key).
Invitation to play: Some dogs bark to say, "Hey, I want to meet/play with you NOW NOW NOW!" (puppy barking frequently falls in this category). These barks are generally high pitched, and are often accompanied by wagging "propeller tails," loose/wiggly body language, play bows and jumping. Ask those who would like to interact with her to wait for calm, quiet behavior before greeting to avoid reinforcing the behavior.
Separation anxiety: True separation anxiety (destruction to self or property) is a topic beyond the scope of this Blog. If your dog is injuring herself or destroying your home, We recommend you seek the assistance of a behaviorist such as Vera Wilkinson from the Cooperative Dog, in addressing this issue.