Journal of Consulting and Clinical Psychology Vol. 86, Iss. 6,  (Jun 2018): 493-504. Objective: Internet-based cognitive–behavioral treatments (ICBT) have shown promise for various mental disorders, including social anxiety disorder (SAD). Most of these treatments have been delivered on desktop computers. However, the use of smartphones is becoming ubiquitous and could extend the reach of ICBT into users’ everyday life. Only a few studies have empirically examined the efficacy of ICBT delivered through a smartphone app and there is no published study on mobile app delivered ICBT for SAD. This three-arm randomized-controlled trial (RCT) is the first to compare the efficacy of guided ICBT for smartphones (app) and conventional computers (PC) with a wait list control group (WL).. To read the full article, log in using your NHS OpenAthens details.