Therapists. Twelve advanced trainees with at least 2 years post-graduate training are recruited from local (CBT)-training centers. The majority of the therapists have experience as study therapists in a prior randomized controlled trial. All the therapists participate in an initial 16-hour workshop presented by the developer of the treatment manual (Zinbarg et al., 2006). In addition to the peer-tutorings (primings), the therapists have regular supervision in small groups on a 14-day basis. The supervision is conducted in mixed groups over the 3 priming conditions. All the supervisors also participate in the initial 16-hour workshop. To respect and coordinate the therapists' preferences (e.g. preferences in working days and time schedules) they were assigned in a joint face-to-face session at study start. All the therapists gave verbal and written consent to the selected peer-tutoring partner and priming condition.