Numerous frameworks and definitions have sought to differentiate what behaviors and experiences should be considered as a part of stuttering. Nearly all of these efforts have been based on the perspectives and beliefs of conversational partners and listeners. This outside-in approach to defining stuttering lacks validation from people who live with the condition. In this study, 430 adults who stutter participated in a qualitative exploration of the term stuttering. Data were analyzed thematically to determine speakers’ perspectives about moment of stuttering and the overall experience of stuttering in their lives. These data are used to update the adaptation of the World Health Organization’s International Classification of Functioning, Disability and Health as it applies to stuttering (Yaruss & Quesal, 2004) to better account for the complex and individualized phenotype of stuttering and to develop a definition of the experience of stuttering that is based not only on the observations of listeners but also on the impact of stuttering on the lives of adults who stutter.