Nineteen adults who stutter participated in a 3-week intensive stuttering modification treatment program (the Successful Stuttering Management Program [SSMP]). A series of 14 fluency and affective-based measures were assessed before treatment, immediately after treatment, and 6 months after treatment. Measures included stuttering frequency; the Stuttering Severity Instrument for Children and Adults, Third Edition (SSI-3); a self-rating of stuttering severity; the Perceptions of Stuttering Inventory (PSI); the Locus of Control of Behavior Scale; the Beck Depression Inventory; the Multicomponent Anxiety Inventory IV (MCAI-IV); and the State-Trait Anxiety Inventory. Statistically significant improvements were observed on 4 of the total 14 measures immediately following treatment and on 4 measures at 6 months posttreatment. Statistically significant improvements observed immediately posttreatment included scores on the SSI and the Struggle, Avoidance, and Expectancy subscales of the PSI. Sustained statistically significant improvements at 6 months posttreatment were observed only on client-reported perceptions of stuttering (the Avoidance and Expectancy subscales of the PSI) and 2 specific affective functioning measures (the Psychic and Somatic Anxiety subscales of the MCAI-IV). The SSMP generated some anxiolytic effects but was ineffective in producing durable reductions of core stuttering behaviors, such as stuttering frequency and severity. The discussion focuses on the strengths, weaknesses, and durability of the SSMP treatment approach.