Social anxiety disorder among youth is highly prevalent and causes significant impairment in the lives of the affected. In spite of cognitive behavior therapy (CBT) being an effective treatment, research suggests that many young people with this disorder do not have access to good-quality CBT. Internet-delivered CBT could be an effective method to increase availability of evidence-based treatments for youth with social anxiety disorder. The primary objective of this study is to test the efficacy of internet-delivered CBT (ICBT) for youth (10 - 17 years) with social anxiety disorder. The investigators aim to conduct a randomized controlled trial with N = 101 participants. Participants will be randomized to either the active treatment arm (guided ICBT) or to a control condition (guided internet-delivered support and counseling). Follow-ups will be conducted at 3 and 12 months after post-assessment.