Purpose: This project sought to develop consensus guidelines for clinically meaningful, comprehensive assessment procedures for people who stutter across the lifespan. Method: Twelve expert clinicians and researchers who have written extensively about stuttering provided detailed descriptions of the type of data that they routinely collect during diagnostic evaluations of preschool children, school-age children, adolescents, and adults who stutter. Iterative content analysis, with repeated input from the respondents, was used to identify core areas that reflect common domains that these experts judge to be important for evaluating stuttering for varying age groups. Results: Six core areas were identified as common components of a comprehensive evaluation of stuttering and people who stutter. These areas should be included to varying degrees depending upon the age and needs of the client or family. The core areas include the following: (a) stuttering-related background information; (b) speech, language, and temperament development (especially for younger clients); (c) speech fluency and stuttering behaviors; (d) reactions to stuttering by the speaker; (e) reactions to stuttering by people in the speaker’s environment; and (f) adverse impact caused by stuttering. Discussion: These consensus recommendations can help speech-language pathologists who are uncertain about appropriate stuttering assessment procedures to design and conduct more thorough evaluations, so that they will be better prepared to provide individualized and comprehensive treatment for people who stutter across the lifespan.