Those first magical days of a puppy's life are amazing to witness, as anyone who has been there can attest. When puppies open their eyes, they are greeted by an amazing assortment of sights. As their eyesight gets better, more of their senses begin to be awakened and they become more interested in exploring the world around them.
The question is, when do puppies open their eyes and start this process. The answer is somewhere between seven days to two weeks after birth. It varies a bit, based on breed and on the puppies themselves. A similar question is often, "When does their hearing start to develop?" When puppies open their eyes, this is just the first step in the beginning of other senses, including hearing. A puppy's ears will begin to "open" soon after their eyes, and both their vision and hearing will continue to improve.
When puppies open their eyes and ears, the next step is usually beginning to walk. Until this point, most puppies crawl around and don't stand on their four feet – much like human babies. After those first couple of weeks however, the puppies will start walking and will quickly advance to trotting and running. At this point, most owners may wish the puppies could return to crawling just to make them more manageable! To learn more about puppies and their first few weeks of life, visit these articles from the Animal Defense League of Texas or the Dumb Friends League (PDF), an animal welfare society based in the Rocky Mountains.
Most people want to know when their puppies will open their eyes because that is really when socialization can begin. Prior to that, the only world the puppy knows is its mother because it knows her smell and her touch. When puppies open their eyes however, they are signaling you that they are ready to begin learning about the world around them. For example, this would be a good time to start picking up the puppies and holding them for a few minutes to get them accustomed to being away from their mother and around humans.
As mentioned above, when puppies open their eyes their hearing starts improving soon thereafter. This event signals a good time to start working on their startle response. When newborn puppies hear a loud noise, they can often become startled and scared. Scared dogs are more likely to bark, growl, and even become aggressive - minimizing their fright as early as possible will go a long way toward alleviating these undesirable responses. One way to adjust a puppy's startle response is simply to expose him to loud noises - for example, clapping your hands loudly near him or dropping pots on the floor. This could be anything that will make a loud noise, but which of course will not cause him any injury.
Another useful situation with which to experiment when your puppies begin opening their eyes is getting them used to a leash. It is unfortunate that some dogs find new homes without ever even seeing a leash - this means their new owners usually face a real challenge in working with them. Just by putting a leash on a puppy for a few minutes each day, then extending the time over the course of a few weeks, will socialize the puppy and make him comfortable with the leash. His new owners will greatly appreciate having a dog who doesn't panic when encountering a leash!