The theoretical basis and practical implementation of software for correlating and updating finite element models with experimental modal analysis is described, with emphasis on the key features and problem areas of these techniques. The validation of a finite element model using a sensitivity-based method and weighted updating of physical parameters of the model in an integrated computer program is described. This enables the analyst to improve the quality and reliability of the FE model and the modeling methodology. Some typical applications are presented, with a detailed case study in which, at first, there is very poor agreement between the analytical and experimental data. It is concluded that these numerical techniques for model updating allow a user to create improved models which represent reality much better than the original ones.