Participants will receive an online synchronous group therapy based on the Unified Protocol (UP) model for 11 subsequent weeks, with 90-minute meetings. After every session, they will be sent the chapter with the notions addressed in the session from the UP's patient manual (Barlow et al., 2011) and the scales to work with during the week.

Participants in the waiting list will complete the evaluation scales at the same time as people in the intervention group (before the intervention, in the middle, after the intervention, three months after and six months after). After this period they will receive the group therapy based on the UP.

The group admission criteria are: 1) being 18 years old or older; 2) submitting the informed consent; 3) agreeing to participate in all the scheduled sessions; 4) agreeing to have the sessions recorded (both audio and video) for oversight purposes; 5) submitting a primary diagnosis of an anxiety disorder (e.g., panic disorder; agoraphobia; social anxiety disorder; generalized anxiety disorder; unspecific anxiety disorder), unipolar depression (major depressive disorder; dysthymia), obsessive-compulsive disorder, or post-traumatic stress disorder, according to DSM criteria and disrupting individuals' daily life or causing significant discomfort.

The group exclusion criteria are: 1) comorbidity with psychotic disorders, bipolar disorder, eating disorders, borderline personality disorder, or active severe suicidal ideation, and 2) currently receiving pharmacological treatment. All candidates who are not included in the group will be informed of this decision and will be given information on places to seek treatment. Evaluations will be carried out via video calls on the Google Meet platform, using the MINI (Ferrando et al., 2000) and SCID-II (Grilo, Anez & McGlashan, 2003) diagnostic interviews.

Inclusion Criteria:

• 1) being 18 years old or older; 2) submitting the informed consent; 3) agreeing to participate in all the scheduled sessions; 4) agreeing to have the sessions recorded (both audio and video) for oversight purposes; 5) submitting a primary diagnosis of an anxiety disorder (e.g., panic disorder; agoraphobia; social anxiety disorder; generalized anxiety disorder; unspecific anxiety disorder), unipolar depression (major depressive disorder; dysthymia), obsessive-compulsive disorder, or post-traumatic stress disorder, according to DSM criteria and disrupting individuals' daily life or causing significant discomfort.

Exclusion Criteria:

• 1) comorbidity with psychotic disorders, bipolar disorder, eating disorders, borderline personality disorder, or active severe suicidal ideation, and 2) currently receiving pharmacological treatment.