This month Kiki Yablon, KPA CTP, writes about what socialization is and why it’s so important.

Many of the serious behavior problems seen in adult dogs are rooted in incomplete or improper socialization. Yet adopters of young puppies often don’t even learn what socialization really is, or why it’s so important, until it’s too late.

Socialization is a process that needs to be well under way before your puppy is 12 weeks old. Between three and four months of age, the developmental stage known as the critical socialization period ends, and your puppy is more likely to be apprehensive about or even fearful of things he has never experienced before—whether or not they are a real threat. As he matures, untreated fear can manifest as anxiety and aggression.

Socialization doesn’t just mean play with other puppies and appropriate adult dogs. It means exposure to people, places, things, sounds, smells, surfaces, other animals, and experiences that he will need to be comfortable with. Your puppy should meet several new people and have several novel experiences every day. He should encounter the mail carrier and heavily perfumed women and smokers and beardos and men in hats. He should make happy visits to the vet and the groomer and take other car rides to nowhere in particular. He should hear thunder and fireworks and trucks, watch a vacuum cleaner and a bicycle and a wheelchair in action, meet a dog-tolerant cat, and walk on grass, concrete, gravel, mulch, and manhole covers. If you live in the city, take a field trip to the country, and vice-versa. Veterinarian Sophia Yin provides a free sample checklist excerpted from her puppy-raising book.

But exposure alone isn’t enough: this exposure needs to be positive. Your puppy needs to learn that all these things are safe, or even better, that they predict good things for him. (This is extra important during “fear periods,” times when a bad experience is more likely to have a lasting effect. The first of these usually occurs between eight and 10 weeks; the second some time during adolescence.) Your job is to create a little canine optimist. Take things at your puppy’s pace and use space to avoid overwhelming him. Don’t force confrontation. Bring treats with you on socialization outings and use them to proactively create positive associations as soon as a new type of thing appears, without waiting for your puppy to get scared.

An excellent resource on how to do this is the book Puppy Start Right, by veterinary behaviorist and veterinary technician Ken and Debbie Martin. (The authors also offer a course for instructors, of which I’m a graduate.)

Finally, enrolling your puppy in a well-run group class before the age of 12 weeks provides not just a wealth of socialization opportunities but also a head start on formal training and professional guidance on common puppy issues. Contrary to older recommendations, puppies should not wait until they are fully vaccinated to attend a class—for more info, check out the current position of the American Veterinary Society of Animal Behavior, the professional organization for veterinarians who specialize in behavior. Operation Socialization’s website provides good advice on protecting your puppy’s health while socializing him.

The process of creating and maintaining positive associations with new experiences shouldn’t stop at 16 weeks. But if your dog is already four months or older and showing fear, the solution may not be the same kind of exposure recommended for puppies who are still in their critical socialization period. Contact a qualified behavior professional to help you get back on track.