Purpose iGlebe is an individualized, fully automated Internet cognitive behavior therapy (CBT) treatment program that requires no clinician contact. Phase I and II trials have demonstrated that it may be efficacious for treating the social anxiety commonly associated with stuttering. The present trial sought to establish whether the outcomes achieved by iGlebe are noninferior to those associated with in-clinic CBT from clinical psychologists. Method Fifty adults with stuttering were randomized to receive in-clinic CBT for anxiety or 5 months online access to iGlebe. The design was a noninferiority randomized controlled trial with outcomes assessed at prerandomization and at 6 and 12 months postrandomization. Primary outcomes were CIDI-Auto-2.1 diagnoses for anxiety and mood disorders and Brief Fear of Negative Evaluation scale scores ( Carleton, McCreary, Norton, & Asmundson, 2006 ). Secondary outcomes included speech, psychology, and quality-of-life measures. Results Outcomes consistently showed clinically significant improvements of around a medium effect size for the cohort as a whole from prerandomization to 6 months postrandomization, which were maintained at 12 months postrandomization. Comparisons between the 2 treatments showed little difference between iGlebe and in-clinic treatment for all primary and secondary outcomes, with last observation carried forward for missing data. Conclusions iGlebe is a promising individualized treatment for social anxiety for adults who stutter and offers a viable and inexpensive alternative to in-clinic CBT with clinical psychologists. An issue to emerge from this trial, which requires clarification during future clinical trials of iGlebe, is the posttreatment relation between percentage of syllables stuttered and self-reported stuttering severity ratings.