Depression is one of the mental health disorders that is into the first causes of disability. Inteenagers, depression rates are high in terms of prevalence and incidence; Behavioral Activation has empirical support for depression. A single case study A-B plus follow-up is presented; It looks for evaluating the effect of the single session BATD protocol, plus strengthening the on-line mode, testing it on 5 Colombian teenagers between 15 and 18 years of age. For the measurement of variables, the following were considered: Daily Monitoring Record, pre and post results of the CES-D Scale. A visual and statistical analysis of the time series was carried out for the frequency of healthy behaviors and averages of enjoyment and importance. For the CES-D, clinically significant change was calculated through the criterion of reliable change. It was proven that the single session BATD plus strengthening online modality to be effective in reducing depressive symptoms in teenagers with light and moderate depression.