The goal of this study is to test the existence of a relationship among some variables of personality and treatment (general self-efficacy, social self-efficacy and number of treatment intents) with chronic sustance use (alcohol, cannabis and cocaine). The participants in the study were 175 polisubstance users (alcohol, cannabis and cocaine). They begun their treatment in 44 treatment and rehabilitation centers in three regions of Bolivia: La Paz, Cochabamba & Santa Cruz.. The assessment instruments applied were the Self-efficacy Scale (Sherer et al., 1982) and the “Informative Interview regarding the Cultural, Professional and Research Level of the Addictive Behavior” by López-Torrecillas (1996). The results show that General Self-efficacy mediates the prediction of chronic alcohol, cannabis and cocaine use. These results point to the need to develop intervention programs devoted to the modification of this psychological variable