@ogrellik88 isn't totally wrong. The Boston Terrier is descended from the now-extinct bull-and-terrier dogs, and bred down over generations to the smaller size we see today. The American Pit Bull Terrier is also descended from these dogs. "Pit bull" is also used as a generic name given to any large breed descended from the bull-and-terriers, such as the APBT, American Staffordshire Terrier, the Staffordshire Terrier, bulldog mixes, etc. It could be argued, then, that because of their very similar ancestry, the Boston Terrier is indeed a bull-type breed. Modern-day Bostons have been bred down to be much smaller than what would be considered a "pit bull", but it looks like Sergeant Stubby was quite a bit bigger, in the very early days of the breed and thus would be closer in appearance to his "pit bull" cousins than a Boston Terrier would today. So, you're both right. He is part of the transition generations. Forgive the Wikipedia articles but they are pretty accurate this time: www.wikipedia.org/wiki/Boston_Terrier Look at the history portion www.wikipedia.org/wiki/Bull-type_terriers