The aim of this study was to evaluate the effectiveness of a brief motivational intervention to change processes against marijuana use in colombian youth through voluntary participation of 15 young people (eight men and seven women), aged between 18 and 23 years, expressing their desire not to continue consuming this substance. The study was conducted under a pre-experimental methodology, with pretest and posttest (M1 X M2) with a single group. For this case, the variations were measured in the psychological processes of change and the willingness to change in a group of 15 young marijuana after brief motivational intervention. Selective prevention program was implemented by the strategy workshop and allowed in each of the sessions follow a structured way strategies derived from TTM. The results indicate that the implementation of brief motivational intervention affected the motivational processes of change associated with marijuana, being effective for the selected sample; they cannot be generalized to the entire population, but contribute to the collection of research regarding the effectiveness of intervention Brief Motivational addiction.