This study aimed to evaluate the effectiveness of two brief intervention protocols: one involving brief systemic therapy and the other involving positive cognitive behavioral therapy. Protocols consisting of six weekly individual sessions were developed and compared with a waiting list control group, targeting individuals who had experienced a highly stressful event in the previous six months. The design was experimental, using a randomized clinical trial. The objective was to reduce associated distress (depressive and post-traumatic symptoms) and increase levels of well-being (life satisfaction and post-traumatic growth). A total of 148 adults participated, referred from various care centers in Chile, who had experienced a highly stressful event within the last six months. The results showed significant differences between the intervention groups and the control group in the four outcome variables measured, with effect sizes ranging from medium to large. Follow-up indicated that the changes produced were maintained or increased nine months after the initial assessment. These results suggest that brief interventions can be effective in reducing distress and promoting well-being in individuals who have experienced a highly stressful event. Their short duration, easy implementation, and low cost make brief interventions a useful alternative for helping people who have difficulty accessing mental health care services, which is common in Latin America. The project was funded by Chile's National Fund for Scientific and Technological Development (FONDECYT).