The Boston Terrier personality varies from individual to individual. Some are rowdy and sassy, others more mellow and subdued, while still others will do anything for a laugh. All Boston Terriers, however, love people, love activity and love lots of attention. They are especially good dogs for elderly people, as they tend to focus most of their attention to one person, and tune in to that person's emotions. A Boston knows when his person is sad, happy, lonely or angry and can adjust his own behavior accordingly.

Curvature of the back, called roaching, might be caused by patella problems with the rear legs, which in turn causes the dog to lean forward onto the forelegs. This might also just be a structural fault with little consequence to the dog. Many Bostons cannot tolerate excessive heat and also extremely cold weather, due to the shortened muzzle, so hot or cold weather combined with demanding exercise can bring harm to a Boston Terrier. A sensitive digestive system is also typical of Boston Terriers. In the absence of good quality, proper diet, flatulence is associated with the breed.  Their large and prominent eyes make Boston Terriers prone to corneal ulcers.

Bostons are brachycephalic breeds. The word comes from Greek roots "Brachy," meaning short and "cephalic," meaning head. This anatomy can cause tiny nostrils, long palates and a narrow trachea. Bostons may be prone to snoring and reverse sneeze—a rapid and repeated forced inhalation through the nose—accompanied by snorting or gagging sounds used to clear the palate of mucus, which does not harm the dog in any way. Brachycephalic dogs may be prone to complications with general anesthesia. Bostons frequently require caesarean section to give birth, with over 90% of litters in a UK Kennel Club survey delivered this way.