Performance-Based Design is accepted commonly as the most advanced design and evaluation approach. However, its successful application depends on the ability to accurately estimate the parameters of structural response. The determination of these parameters requires applying analysis procedures where the non-linear behavior features of structures are included. This chapter presents and discusses these features of non-linear behavior and how they are incorporated in the process of static or dynamic structural analyses. Non-linear analysis allows obtaining from the seismic response significant structural response parameters such as ductility, overstrength, response reduction factor and damage thresholds. In order to illustrate the application of the non-linear analysis procedures, a set of concrete-reinforced moment-resisting framed buildings with various numbers of levels, was designed according to ACI-318 for high and very high level of seismic hazard. Their seismic safety is studied using both the static and dynamic non-linear analyses.