A research project was undertaken to determine the painting techniques used by the Mexicas in their creation of wall-paintings at the Great Temple of Tenochtitlan in Mexico City. Fifty-four samples, from wall-paintings in various pre-Hispanic buildings, were analyzed by means of several techniques. Replicas were also fabricated so that the characteristics of various painting techniques could be observed and compared with the historic samples. The results showed that the pigments from most of the wall-paintings on mud plaster had been applied over wet mud, probably using limewater or lime milk. In the case of the wall-paintings on lime plaster, several painting techniques were used, including painting fresco. Future research is needed to determine whether an organic binder was used in several wall-paintings. -- SCMRE