Post-traumatic stress disorder (PTSD) is a mental health condition that's triggered by the experience of potentially traumatic events. A complex PTSD (CPTSD) includes additional symptoms that account for a disturbance of the organization of the self. Randomized controlled trials have shown that trauma-focused cognitive behavioral therapy (TF-CBT) is effective in reducing PTSD symptoms; however, there is insufficient evidence to support the effectiveness of this intervention for CPTSD. The present study aims to evaluate the feasibility, acceptability, and preliminary effectiveness of TF-CBT therapy for complex presentation (TF-CBT-CP) in videoconference modality compared with the usual treatment for the reduction of PTSD and CPTSD symptoms in adults diagnosed with PTSD or CPTSD, who are treated at the community mental health care services (CMHCS, COSAM in spanish) of the Maule Region, Chile. This pilot study will use a mixed design. The quantitative component will consist of a randomized two-arm parallel superiority trial, blinded to the data analyst, which will include 68 adults diagnosed with PTSD or CPTSD referred to care at CMHCS of the Maule Region, Chile. The collection of qualitative data related to the study's acceptability will be done through telephone interviews. Participants will be randomized into experimental (EG) or control (CG) groups in a 1:1 ratio. Participants in the EG will receive TF-CBT-CP therapy. It consists of 16 weekly 60-minute sessions of trauma-focused cognitive behavioral therapy for complex presentations. People who take part in the CG will get the same treatment (TAU) that CMHCS gives to people who are referred for PTSD symptoms or problems related to traumatic events. This could mean waiting on a list, getting medication, and/or going to regular non-specialized PTSD therapy sessions. To determine the feasibility of TF-CBT-CP therapy, eligibility, recruitment, participation, activity completion, retention, exit, and dropout rates will be considered. To establish the acceptability of the protocol, participant satisfaction with the recruitment, assessment, and treatment process and reporting of reasons for non-participation or dropout will be assessed. Secondary outcomes of preliminary effectiveness consider the reduction of PTSD and CPTSD symptomatology, depression, anxiety, and improvement of indicators of emotional regulation and psychological well-being.