Participants will be randomized to either stepped care ICBT or to gold standard face-to-face CBT. One group (stepped care) will be first offered ICBT for 16 weeks. Non-responders at the 3-month follow-up will receive additional face-to-face CBT. The other group (gold standard treatment) will be randomized directly to receive face-to-face CBT for 16 weeks. Non-responders will, as in the other group, receive additional face-to-face treatment after the 3-month follow-up. The primary endpoint will be at 6-month follow-up. Long-term effects are also investigated (1 year, 2 years and 5 years after treatment completion).