The aim of this study was to develop an Irrational Beliefs Inventory for adolescents (TCI-A). This inventory included one scale of Irrationality and six subscales of irrational beliefs: Need for Approval/Success, Helplessness, Blame Proneness, Avoiding Problems, Intolerance to Frustration and Justification of the Use of Violence. The participants were 856 adolescent students (Mean age= 15.92 years old). They completed the irrational beliefs subscales together with the Youth Self Report (YSR; Achenbach, 1991) and the Social Problem Solving Inventory-Revised (SPSI-R; D´Zurilla, Nezu & Maydeu-Olivares, 1998). The confirmatory factor analysis showed that the structure suggested for TCI-A was adequate. Irrationality results correlated with behavior problems. Most remarkable were the associations between the Need of Approval/Success subscale, and the Internalizing Syndrome and the Justification of the Use of Violence and Externalizing Syndrome. Finally, the Need of Approval/Success and the Helplessness subscales were associated with the Negative Problem Orientation.