Do you have a new puppy? Its first three months of life are a critical time in its development. This is the time when it will develop lasting positive or negative associations with its world. Your puppy’s brain is highly adaptable and it is a great time to set the foundation for the rest of its life.
After this period, your puppy can become wary of unfamiliar stimulus in its environment.
A puppy that has not had positive experience with a lot of different people, dogs, and things will 
never reach its full potential and will be more likely to move away from, bark, lunge or growl at the unfamiliar into adulthood.
Part of this also includes teaching your puppy self-control, manners and focusing back on you in different environments.
Last week, I was with this adorable Bernese Mountain Dog puppy and his human parents at a local park where he experienced all kinds of surfaces, a playground, seeing a variety of dogs on leashes, a man using an electric wheelchair, a man using a walker, kids of all ages (some running around, some walking, and a group sitting on the ground playing cards). We carefully monitored his body language, managed his interactions to ensure they would be positive ones, and had fun. He also had practice walking and paying attention to his owners. These types of experiences are already having a positive impact on his development.
I have more on socialization in this blog post.
