Modal analysis is one of the most powerful tools available to the engineer for the dynamic analysis of structures. Development has been rapid and spans the identification and evaluation of vibration phenomena, the validation, correction and updating of analytical models and the assessment of structural integrity. The texts assembled here form a coheren t work. After a first chapter on the fundamentals of modal analysis, the reader is introduced to signal processing and the basic rules of exchange and analysis of dynamic information. The derivation of theoretical models for modal analysis is then addressed, followed by three chapters on the different approaches to the derivation of models based in the identification of experimental data: time domain, frequency domain and pseudo-testing. This leads to the discussion of updating analytical models and to model quality assessment techniques. Further topics treated include damage detection and evaluation, structural modification, damping modelling, and the normalisation of complex modes. Less well-known topics are also included: active control of structures, acoustic modal analysis and neural networks for modal analysis, advanced optimization methods of model updating, modal analysis for rotating machinery, and nonlinearity in modal analysis.