The primary objective of the research is to develop a methodology for practical and reliable identification of analytical models of engineered structures. The methodology is based on the complex interrelationship between (1) an initial model, (2) experimentation and data processing, (3) algorithms to extract global response parameters and to estimate local characteristics, and (4) procedures to update the model through an iterative process. The novel feature of the idea is to implement step-by-step identification procedures based on test results of several laboratory specimens. The specimens are selected with known or controlled characteristics. In each step the source of error and uncertainty is investigated and dealt with. Initial specimens considered will be comprised of several cracked prestressed or reinforced concrete beams with different distributions of stiffness, support flexibility, and continutity.