In this chapter we review the literature on internet-delivered treatment for social anxiety disorder (SAD). There are several different treatment programs that have been tested in randomized controlled trials and evidence now suggests that guided internet-based cognitive behavior therapy (ICBT) can be as effective as face-to-face therapy, that therapists may need less training than in face-to-face treatment, and that ICBT works in representative clinical settings, thereby supporting effectiveness. Moreover, there are studies to suggest that ICBT has enduring effects up to five years after treatment and that it is cost-effective. Since there are advantages with internet treatments, this treatment option should be considered as a complement or alternative to face-to-face treatments for SAD. Treatment mechanisms, including moderators and mediators of outcome, remain to be investigated.