7Constitutive models for masonry require a number of parameters to define material behaviour 8 with sufficient accuracy. It is common practice to determine such material parameters from 9 the results of various, relatively simple, small-scale laboratory experiments. However, the 10 effectiveness of determining material parameters that are representative of masonry from 11 small-scale experiments have found to be problematic. This paper investigates the material 12 parameter identification problem for masonry constitutive models. The methodology is based 13 on an inverse analysis containing an optimization procedure and surrogate modelling. The 14 general framework of the non-linear estimate methodology and the parameter identification 15 problems are discussed. 16 17