The control group is made up of participants who are eligible but not assigned to the treatment. For ethical reasons they will be able to access the intervention once the experimental group has concluded the study. During the waiting-list phase, participants can access a mental health intervention, but in this case they are excluded from the study. Participants are told that there is only one possible active group and therefore a waiting-list is created. This explanation is given to reduce a worsening symptom bias for feeling "excluded" from treatment.

The experimental intervention is an integrative mindful compassion group therapy as manualized by Cheli, Cavalletti, Flett & Hewitt (2020). The structure was outlined on the base of standard mindfulness-based interventions, comprising eight 2-hour online group sessions and one day of silence lasting 4 hours. The contents and the phases of the intervention were rooted in two different frameworks. On the one hand, the sequence of and the types of practices were defined in accordance with the mindful compassion protocol (Gilbert & Choden, 2014). On the other hand, the shared conceptualization of perfectionism and its role in triggering, maintaining, and inducing relapses in personality disoders was proposed through the relational model by Hewitt and colleagues (2017). The hybrid format (online weekly sessions plus an in presence half-day of silence) has been developed in accordance with existing COViD-19 emergency and rules.

The experimental intervention is an integrative mindful compassion group therapy as manualized by Cheli, Cavalletti, Flett & Hewitt (2020). The structure was outlined on the base of standard mindfulness-based interventions, comprising eight 2-hour in presence group sessions and one day of silence lasting 4 hours in presence. The contents and the phases of the intervention were rooted in two different frameworks. On the one hand, the sequence of and the types of practices were defined in accordance with the mindful compassion protocol (Gilbert & Choden, 2014). On the other hand, the shared conceptualization of perfectionism and its role in triggering, maintaining, and inducing relapses in personality disoders was proposed through the relational model by Hewitt and colleagues (2017).

The intervention is a 8-week group psychotherapy in a hybrid format: 8 weekly online sessions lasting 2 hours plus an in presence half-day of silence lasting 4 hours.

Feasibility is defined on the basis of two criteria: absence of adverse events (i.e. dropouts; hospitalization; etc.) and adequate adherence (i.e. maximum 1 skipped session per participant)

At the final assessment, the experimental group's Perfectionistic Cognitions Inventory (PCI) scores are significantly lower than those of the control group (the differences in the initial assessment must be insignificant). Higher scores of PCI (ranging between 0 to 100) are indicative of higher perfectionistic worry

In the experimental group the scores on the Perfectionistic Cognitions Inventory (PCI) must show a significant difference between initial and final assessment. Higher scores of PCI (ranging between 0 to 100) are indicative of higher perfectionistic worry