It's a good question. There are two perspectives to take on this: legal and personal. Legal: According to the American's with Disabilities Act (ADA) A disability is ["a physical or mental impairment that substantially limits one or more major life activities of such individual"](http://www.ada.gov/pubs/adastatute08.htm#12102). Stuttering is a physical impairment that impedes on a major life activity (speech). So legally, stuttering is a disability. Personal: The degree to which a person perceives stuttering to cause disability in his/her life is not consistent across people (I don't have data supporting this, this is just my clinical judgement). This personal definition of disability is an interesting question. If I had to guess, I'd say it's inextricably linked with temperament and personality. But that is merely speculation. I don't know of any data attempting to parse out whom is more likely to view stuttering as a "disability."