The socio-demographic and psychosocial approval determinants of the work conducted by the truth and reconciliation commissions (TRC) are analysed based on original survey data from Chilean, Argentinian and Peruvian samples (N = 2,947). A linear multiple regression analysis was carried out (R2 between.28 and.44; f2 between.45 and.78) which reveals the positive effect of commission functions perceived achievement, mainly the knowledge of truth (β = .28), justice (β = .15) and the contribution in creating a common history (β = .15). An analysis by country reveals in Chile salient variables such as institutional trust, political ideas, institutional apologies and hope and sadness emotions. In Argentina, together with TRC functions, the degree of information about the work of the commission and the perception of a negative social climate appear as relevant predictors. As regards Peru, the degree of exposure to violence appears as a good predictor of TRC’s work support. The results show the relevance of TRC functions’ fulfillment, as well as the role of institutional variables in the approval of the work they have done.